Apparatus and method for intelligent routing of data between a remote device and a host system

ABSTRACT

An apparatus and method is provided for transparent communication between a remote or mobile device and a fixed communication host network. The apparatus and method may include a remote network controller that logically resides between the host network and the existing infrastructure(s) that are used to provide communications network contact with one or more remote devices. The remote network controller is connected to the host communication network as a protocol-appropriate communications controller so that remote devices are indistinguishable to the host network from the locally-attached devices. Each remote device may be provided with an asynchronous serial data interface to communicate with a mobile data controller. The mobile data controller, in combination with the remote network controller, provides end-to-end data communication such that incompatible protocols are transparent to the remote device and host communication network. A router may be provided which selects a communications network in accordance with user configured parameters. The router communicates over a plurality of incompatible networks and is capable of using a variety of different protocols. Switching between the plurality of incompatible networks is transparent to the remote device and host communication network.

CONTINUING AND RELATED APPLICATION DATA

This is a continuation of U.S. patent application Ser. No. 08/932,532,filed Sep. 17, 1997, which is a continuation-in-part application of U.S.patent application Ser. No. 08/456,860, filed on Jun. 1, 1995, entitled“Apparatus and Method for Transparent Wireless Communication Between aRemote Device and a Host System,” now U.S. Pat. No. 5,717,737 thedisclosures of which are expressly incorporated herein by reference intheir entireties.

BACKGROUND OF THE INVENTION

1. Field of Invention

The present invention relates to the transportation of data throughdissimilar communications media. More particularly, the presentinvention relates to an apparatus and method for transporting databetween a remote mobile or fixed terminal device and a host system overmultiple, dissimilar communications media. The communications media overwhich the data is transported include wireless data links, wired datalinks or a combination of wireless and wired data links which areselected based upon a set of preference metrics.

2. Background Information

The ability to transport data between mobile and/or fixed terminaldevices and host computer systems have been generally available for manyyears. Networks designed to transport this data currently exist in awide variety of wireless and wired network architectures. Both apparatusand method exists for transporting data through multiple, similar mediatypes as well as the automatic selection of alternate communicationpaths based upon a plurality of preference metrics.

Often, when multiple networks are available from a common location suchas a vehicle, great benefit may be derived by allowing uniformcommunications through all available networks. Certain networks mayperform better for bulk data transfers where another may performinteractive messaging in an optimal fashion. One network may bepreferable because of its low cost but an alternate, more expensivenetwork may be acceptable as a backup if the low-cost network isunavailable.

Other examples include U.S. Pat. No. 5,412,375, to WOOD, which disclosesa system for selecting one of a plurality of interfaces to a singlewireless communications system in accordance with the capabilities of asubscriber unit and the capabilities of a base unit. A list of airinterface capabilities of the subscriber unit and the base unit arecompared by a controller to determine a compatible interface. Asdisclosed in WOOD, the plurality of air interfaces include Analog MobilePhone System (AMPS), Time Division Multiple Access (TDMA) and CodeDivision Multiple Access (CDMA). While the WOOD system does select fromone of a plurality of interfaces which may be applicable for datacommunication, the routing decision is based on the capabilities of theendpoints rather than the preference metrics of the transportingnetworks. The endpoint devices, in this case, must be aware of thepeculiarities of the wireless environment.

U.S. Pat. No. 5,420,574, to ERICKSON et al., discloses a subscriber unitattached to a trunked mobile radio having a data input. The mobile radiocommunicates both voice and data message formats over a wireless networkto a base station via channels that are allocated by a trunked datacontroller which is connected to a host network. Channel states andcommunication parameters are set in accordance with the type ofinformation (e.g., voice or data) that is being transmitted or received.While the ERICKSON et al. system dynamically switches betweenincompatible message formats without the intervention of the endpointdevices, only a single data path is provided. In addition, theincompatibility of the two alternate paths arises from a difference inmessage formats rather than the use of independent, incompatiblenetworks.

Further, the transportation of data through alternate, incompatiblecommunications media is a problem that does not have a uniform solutionin the art. This problem is exacerbated in wireless communicationnetworks where protocols, timing and other incompatibilities render anotherwise acceptable level of service inadequate. Attempts to providedata links through incompatible networks have suffered from the sameobstacles that hindered data communications prior to open standardsbecoming widely accepted, i.e., proprietary protocols visible to theendpoint terminal devices make the devices inflexible and expensive andthe interoperation of similar devices with incompatible networkingcomponents is difficult and complex.

Networks may be interconnected by routers which operate at the networklevel and convey messages between compatible networks. Routers makelogical decisions about the pathway through which data is to be directedin the networks based upon a variety of preference metrics. A router isgenerally implemented as an autonomous device with multiple connectionsto the networks through which data is to be routed. Routers operate atthe network layer and can recognize and manage protocols and multipleconnections to networks. Routers usually operate in accordance with theaddress provided by the particular protocol of the network, and normallyprovide routing between and through networks utilizing the same networkprotocol and can route between networks that use different data-linklayers, such as Ethernet, Token-Ring, Serial PPP, etc. Another type ofrouter includes two routers loosely-coupled through a protocol-neutraldata-link, where the linked routers are considered as a single “virtual”router.

Dissimilar networks may be connected by gateways which are devices thatinterconnect two or more dissimilar networks. A gateway differs from arouter in that the endpoint terminal devices may implement a dissimilaror incompatible protocols. Gateways often perform specific protocolconversions at the layers above the network layer to move data from onetype of network to another. In this regard, the Open SystemsInterconnection (OSI) model includes seven “layers” to providecommunications between heterogeneous (i.e., incompatible) systems. Thelayers, from lowest to highest, are: the physical layer, the data linklayer, the network layer, the transport layer, the session layer, thepresentation layer, and the application layer. Each of the layersperforms a specific task in transporting data between two or moreentities. Such a layered structure is shown in The TCP/IP Companion, byMartin R. Arick, Wiley-QED, pp. 18-19.

U.S. patent application Ser. No. 08/456,860, to DOVIAK et al., forexample, discloses a system in which a distant mobile or fixed terminaldevice transports data through a plurality of wireless network to anendpoint which may or may not implement the same network protocol as thedistant device. However, while the DOVIAK et al. system is capabletransmitting data over a plurality of dissimilar wireless communicationsnetworks, the system does not automatically transmit data throughdiffering ones of a plurality of dissimilar networks in accordance withpreference metrics to reach the data-link endpoints. Thus, the systemdoes not automatically provide redundant or alternate pathways throughwhich data may be delivered.

U.S. Pat. No. 5,537,220 to EZUMI et al., discloses a portable facsimileapparatus provided with a capability to communicate over a plurality ofcommunications lines. As disclosed in EZUMI et al., the facsimilemachine may communicate over telephone lines or a mobile communicationunit. A NCU (controller) is provided within the facsimile machine todiscriminate whether the facsimile machine is connected to the telephoneline or to the mobile communication unit. The NCU functions to adjustthe data rate, and transmitting and receiving signal levels based onwhich communication system it is communicating. Although this conceptmay be extended to a generic protocol-neutral data networkingenvironment, the EZUMI et al. system provides for the selection of onlyone single path to the exclusion of other, possible viable path basedsolely on which link is plugged into the NCU. Further, the EZUMI et al.system does not switch communication paths within the boundaries of acommunication session thereby further limiting its usefulness in aconnectionless, packet data environment such as a TCP/IP network.

U.S. Pat. No. 5,602,843, to GRAY, discloses a PBX-based integratedtelecommunications system having a wired subsystem connected to wiredterminals, and a wireless system for connecting to mobile terminals. Acontroller is provided which manages base stations and communicates towireless handsets. When communicating to a handset, the controllerdetermines which base station is in communication with the handset anddirects the base station to send packet-based information to thathandset. A separate PBX controller is provided to communicate with thewired terminals. The PBX controller includes a proximity sensor todetect wireless handsets such that when a handset is detected inproximity to a wired terminal, messages are forwarded to the wiredterminal rather than the wireless handset. While the GRAY systemdynamically selects the route to a terminal device based upon apreference metric (wireless proximity), the alternate routing techniquedoes not address transporting data between the same two endpoints. Inaddition, GRAY provides no means to provide alternate path routing for aterminal device through either the wireless or wired handsets.

U.S. Pat. No. 5,452,471, to LEOPOLD et al., discloses a communicationsystem having a primary and one or more subordinate communicationsystems. In the illustrated embodiment, the primary communication systemis a satellite-base communication system having the widest area ofcoverage. Each of the satellites within the system defines a cell areawhich moves as the orbiting satellites move. The secondary and tertiarycommunications systems are disclosed as terrestrial based, stationarysystems having base stations fixed near the surface of the earth (e.g.,fixed to a building), where each subordinate system has an increasinglysmaller region of coverage. The secondary and tertiary systems include acontroller located at a monitoring location within each region. Each ofthe communications systems includes a link to a central office to enablecommunications over the public switched telephone network. The LEOPOLDet al. communication systems and mobile subscriber units operate withinone frequency spectrum, however, the primary and secondary communicationsystems operate together by using orthogonal channels to preventinterference. In addition, when communicating with secondary systems,the mobile subscriber unit transmits at a relatively low power such thatthe primary system will not receive the transmission. The mobilesubscriber unit is programmed to utilize the communication system havingthe smallest area of coverage such that if the subscriber unit has threecommunications systems available, the subscriber unit will utilize thetertiary communications system (i.e., the system having the smallestarea of coverage) based on a designed assumption that the moresubordinate the communication system is, the higher the capacity of thesystem. While the system of LEOPOLD et al. dynamically selects a routebased upon a set of preference metrics such that the terminal endpointsare unaware of the routing selection, a common data-link protocol isrequired throughout all possible associated networks. In addition, thewireless frequencies employed must be derived from a continuous,compatible set of frequencies which prevents the device from selectingamong inherently incompatible networks.

Despite the teachings of these prior attempts, users of mobile or fixedwireless data communications are provided with systems of limitedcapacity and flexibility when routing data through more than onenetwork. In addition, such systems require special hardware and/orsoftware developed for and compatible with the networks, which mayrequire additional training of support personnel and end-users. Further,users of wireless mobile data communication services are provided withonly a limited ability to control costs associated with sending andreceiving data to and from remote devices, and are limited in theirhardware and software design implementations. In previous teachings, thecandidate networks must be compatible with one another at either thenetwork or the data-link level. Thus, routing data through inherentlyincompatible networks such as Cellular Digital Packet Data (CDPD) andEricsson EDACS is not possible as these are incompatible at both thedata-link and network levels. Moreover, known systems do not allow acustomer to use existing RF wireless infrastructures, including existinghardware and software, with only minor modifications needed to transportdata from a mobile device to a host computer network. In addition, pastattempts do not permit wireless data communications in a manner that istransparent to the remote device. Further, prior systems do not providethe flexibility to users such that a plurality of different remotedevices may communicate with the wired host network irrespective of theradio infrastructure and transmission protocol employed. Such features,without the above-noted drawbacks, would be highly desirable to provideflexibility and ease of use, and to give users of portable data devicesgreater control over their hardware and software design.

SUMMARY OF THE INVENTION

In view of the foregoing, the present invention, through one or more ofits various aspects, embodiments and/or specific features orsub-components thereof, is thus presented to bring about one or moreobjects and advantages, such as those specifically noted below.

A general object of the present invention is to provide an apparatus andmethod for transporting data from a remote, wireless device to a wirednetwork. Another object of the invention is to provide a remote devicewith an interface to present data to the wired network through RFwireless communication.

More particularly, an object of the present invention is to provide anapparatus that resides between an existing wired communications networkand an existing radio-frequency network to provide a wireless RFconnection between a remote device and the wired network.

Another object of the present invention is to provide an apparatus andmethod for a completely transparent data path between a remotely locateddevice and an existing wired network using a wireless RF communicationslink without either the remote device, or the wired network being awarethat a wireless RF communications link is being employed.

Still another object of the present invention is to provide an apparatusand method for a completely transparent data path between a remotelylocated device and an existing wired network through a plurality ofdifferent wireless RF communications link protocols and a plurality ofdifferent wired networks protocols selected by the user.

Still another object of the present invention is to provide an apparatuswhich functions as a protocol-appropriate communications controller andmakes remote devices indistinguishable from locally attached devices toa wired network.

According to one aspect of the present invention, an apparatus fortransporting data between a remote device and a host communicationnetwork using a wireless communications link is provided. The apparatuscomprises a mobile data controller connected to the remote device andthe wireless communications link. The mobile data controller comprises aremote data conversion means for converting data to be transportedbetween the remote device and the host communication network. The remotedata conversion means converts the transported data between a remotedevice transmission format utilized by the remote device and a wirelesslink transmission format utilized by the wireless communications link.

The apparatus also comprises a network interface means for interfacingthe host communication network with the wireless communications link.The network interface means comprises a wireless link conversion meansfor converting the transported data between the wireless linktransmission format and a network interface format utilized by thenetwork interface means; and a host network conversion means forconverting the transported data between the network interface format anda host network format utilized by the host communication network.

The apparatus further comprises a means for transporting the transporteddata over the wireless communication in accordance with the wirelesslink transmission format, the wireless link transmission format and thehost network format being incompatible. According to another aspect ofthe present invention, the network interface means comprises a remotenetwork controller that logically resides on the host communicationnetwork and performs the functions of a network communicationcontroller.

According to another aspect of the present invention, the apparatus fortransporting data further comprises a plurality of network interfacemeans connected by a local network and a synchronization means forsynchronizing the transfer of information between the network interfacemeans, the information comprising routing tables and health and statusinformation.

According to the present invention a method of transporting data from amobile device to a host network is provided. The remote device and awireless communications link are connected by a mobile data controller,and the host communication network and the wireless communications linkbeing interfaced by a network interface device.

The method includes the steps of: converting, at the mobile datacontroller, data to be transported between the remote device and thehost communication network, the converting step converting thetransported data between a remote device transmission format utilized bythe remote device and a wireless link transmission format utilized bythe wireless communications link; transporting the transported data overthe wireless communications link in accordance with the wireless linktransmission format; receiving, at the network interface device, thetransport data from the wireless communications link; converting, at thenetwork interface device, the transported data between the wireless linktransmission format and a network interface format utilized by thenetwork interface device, the wireless link transmission format and thehost network format being incompatible; further converting, at thenetwork interface device, the transported data between the networkinterface format and a host network format utilized by the hostcommunication network; and forwarding the transported data to the hostcommunication network in accordance with the host network format.

In a preferred embodiment, the transportation step further comprisesdetermining wireless communications link selection criteria; dynamicallyselecting a wireless communications link from a plurality ofincompatible wireless communications links in accordance with theselection criteria; and switching to the selected wirelesscommunications link. Afterwards, the following steps are continuouslyrepeated: dynamically selecting a next wireless communications link fromthe plurality of incompatible networks in accordance with the selectioncriteria; determining whether to switch wireless communications links;and switching to the next wireless communications link in response to aresult of the determination.

According to another aspect of the present invention, an apparatus fortransporting data over a plurality of incompatible networks between afirst device and a second device is provided. The apparatus comprises asystem for determining network selection criteria. In addition, theapparatus comprises a selection system for dynamically selecting anetwork from the plurality of incompatible networks in accordance withthe network selection criteria and a switching system for switching tothe selected network to use for data transport.

According to another aspect of the present invention, the apparatustransports data via a plurality of protocols over a plurality ofincompatible networks in which the transportation of data is transparentto the first and second devices and to an end user. The protocols mayinclude but are not limited to Internet Protocol (IP) and transparentprotocol.

According to another aspect of the present invention, the apparatus fortransporting data further comprises a system interfacing protocolizeddata into a plurality of incompatible networks using differentprotocols.

According to another aspect of the present invention, the switchingsystem switches networks during the time between the transport ofconsecutive data packets.

According to another aspect of the present invention, the system fordetermining network selection criteria uses two classes of parameters todetermine the next network to use for transport of data.

According to another aspect of the present invention, the selectionsystem further determines a next network to switch to from the pluralityof incompatible networks in accordance with the network selectioncriteria, when the selected network becomes unavailable. In addition, amonitoring system is provided which monitors the availability of theincompatible networks to determine whether the next network is availablefor data transport.

The above-listed and other objects, features and advantages of thepresent invention will be more fully set forth hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is further described in the detailed descriptionwhich follows, by reference to the noted plurality of drawings by way ofnon-limiting examples of preferred embodiments of the present invention,in which like reference numerals represent similar parts throughout theseveral views of the drawings, and wherein:

FIG. 1 illustrates a general overview of a remote network controller andmobile data controller in accordance with an aspect of the presentinvention;

FIG. 2 illustrates a block diagram of the basic components of the remotenetwork controller and mobile data controller of the present invention;

FIG. 3 is a high-level flow chart, according to the present invention,of the outbound data from a wired communication network to a remotedevice;

FIG. 4 is a high-level flow chart, according to the present invention,illustrating the flow of inbound data from a remote device to a wiredcommunication network;

FIG. 5 illustrates a block diagram of the components of a mobileinterface in accordance with the present invention;

FIG. 6 is a flow chart of the processing of an event handler andmultithreading dispatcher associated with the mobile interface of thepresent invention;

FIG. 7 is a flow chart for indicating the process flow of a processinitialization module associated with the mobile interface of thepresent invention;

FIG. 8 is a flow chart for indicating the processing of a mobile sessionmanager associated with the mobile interface of the present invention;

FIG. 9 is a flow chart of the processing steps for an inbound data eventhandler associated with the mobile interface of the present invention;

FIG. 10 is a flow chart of the processing steps for an outbound dataevent handler associated with the mobile interface of the presentinvention;

FIG. 11 is a flow chart of the processing steps for a processtermination module associated with the mobile interface of the presentinvention;

FIG. 12 is a flow chart of the processes associated with a host datacontroller interface module associated with the mobile interface of thepresent invention;

FIG. 13 is a block diagram of the various components of a host datacontroller in accordance with an aspect of the present invention;

FIG. 14 is a block diagram of the components comprising a serviceinterface according to the present invention;

FIG. 15 is a flow chart of the processing of an event handler andmultithreading dispatcher associated with the service interface of theinvention;

FIG. 16 is a flow chart describing the process flow of a processinitialization module associated with the service interface of theinvention;

FIG. 17 is a flow chart of the processing steps for an inbound dataevent handler associated with the service interface of the presentinvention;

FIG. 18 is a flow chart of the processing steps for an outbound dataevent handler associated with the service interface of the presentinvention;

FIG. 19 is a flow chart of the processing steps for a processtermination module associated with the service interface of the presentinvention;

FIGS. 20, 21, 22, 23A, 23B and 24 are flow charts of the variousprocesses associated with a wired communication network interface moduleassociated with the service interface in accordance with the presentinvention;

FIG. 25 is a block diagram of the various components of a mobile datacontroller of the present invention;

FIG. 26 is a block diagram of the various components of a remote gatewayaccording to another aspect of the present invention;

FIGS. 27 and 28 illustrate a block diagram of a remote networkcontroller in accordance with still another aspect of the presentinvention, in which a subsystem synchronization process module isutilized;

FIG. 29 illustrates a general overview of another embodiment of thepresent invention which includes a mobile router in accordance with anaspect of the present invention;

FIG. 30 illustrates a schematic block diagram of the mobile router inaccordance with an aspect of the present invention;

FIG. 31 is an illustration of a block diagram of the functionalcomponents of the router in accordance with an aspect of the presentinvention;

FIG. 32 is an illustration of a block diagram of the switch within therouter according to the present invention;

FIG. 33 is an illustration of a flow chart of the processing steps usedby the router to initialize and build tables stored in the Router inaccordance with an aspect of the present invention;

FIG. 34 is a flow chart of the processing steps used by the router forchecking availability of each network interface in accordance with anaspect of the present invention;

FIG. 35 is a flow chart of the processing steps used by the router toaccount the availability of the channels and the user's configuration inorder to decide which channel to use for transporting data in accordancewith an aspect of the present invention;

FIG. 36 is a flow chart of the processing steps used by the router foran error handler in accordance with an aspect of the present invention;and

FIG. 37 is an illustration of the software architecture of the Router inaccordance with an embodiment of the present invention.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Referring now to the accompanying drawings, FIG. 1 illustrates a generaloverview of a remote network controller and a mobile data controller inaccordance with an aspect of the present invention. In FIG. 1, a wiredcommunication network 10 is shown as a host network system havingcommunications controllers 15 and locally-attached devices 12. The wiredcommunication network 10 may be, for example, a Token Ring network or anEthernet Local Area Network (LAN). The locally-attached devices 12 mayinclude a personal computer, a workstation, a printer or network server,and reside at a plurality of dispersed locations. According to thepresent invention, a remote network controller 20 may also be providedwhich logically resides on the wired communication network 10 and actsas a protocol-appropriate communications controller to send and receivedata to and from the communications network 10 and one or more remote ormobile devices 52. For purposes of illustration, only one of the remotedevices 52 is shown in FIG. 1.

Remote devices 52 communicate via a mobile data controller 54 and awireless radio-frequency (RF) communications link 55 created by theuser's radio infrastructure 56 to the remote network controller 20. Themobile data controller 54 may convert asynchronous data from the remotedevice 52 into an appropriate protocol format of the radioinfrastructure 56. In accordance with an aspect of the presentinvention, the remote devices 52, although not physically connected tothe wired communication network 10, are logically connected to the wiredcommunication network 10 through the radio infrastructure 56 and theremote network controller 20 and are indistinguishable fromlocally-attached devices 12. The remote devices 52 may be, for example,a laptop computer, personal digital assistant (PDA), a credit cardreader, or a global positioning system (GPS) receiver. The radioinfrastructure 56 may comprise a conventional point to point or trunkingradio system.

The logical connection created by the remote network controller 20between the remote device 52 and the wired communication network 10 is“transparent” to the user of the remote device 52, and to the wiredcommunication network 10. In accordance with an aspect of the invention,the remote network controller 20 takes data transported by the radioinfrastructure 56, irrespective of the format protocol of the radioinfrastructure, and converts the data into a format protocol recognizedby the wired network 10. Similarly, the remote network controller 20 ofthe present invention takes data from the wired network 10 and convertsthe data into a format protocol recognized by the radio infrastructure56. Accordingly, the user of the remote device 52 does not have toperform any additional steps to send and receive data to and from thewired communication network 10, and the wired communication network 10does not have to perform any additional steps to send and receive datato and from the remote device 52. The user of the remote device 52interacts with the wired communication network 10 in a similar manner asa user of the locally-attached devices 12. Similarly, the wiredcommunication network 10 interacts with the remote device 52 in asimilar manner as the wired communication network interacts with thelocally-attached devices 12.

Referring now to FIG. 2, there is illustrated a block diagram of thebasic components of the remote network controller 20 of the presentinvention. Each component of the remote network controller 20 will begenerally described for introductory purposes and will later bedescribed in greater detail below with reference to the accompanyingdrawings. The various components of the host data controller 22 and themobile data controller 54 will also be discussed hereinafter withreference to FIGS. 13 and 25, respectively.

As shown in FIG. 2, the remote network controller 20 may comprise aservice interface 30, a mobile interface 24, an interprocesscommunication manager 28, a control process module 26, and a consoleinterface 34. The remote network controller 20 may be implementedthrough a collection of software program modules and hardware componentsworking cooperatively. The remote network controller 20 itself may runon a standard platform, such as a personal computer (PC) equipped with acommercially available processor or multi-processor, e.g., an Intel orMotorola based processor or multi-processor, and a commerciallyavailable operating system, such as an MS-DOS or UNIX based operatingsystem. The remote network controller 20 may also contain an Ethernetcontroller or suitable network controller card depending on the wiredcommunication network 10. In addition, the remote network controller 20may include random access memory and physical storage media includinghard disk and tape storage devices.

The wired communications network 10 is connected to the remote networkcontroller 20 by the service interface 30. The service interface 30handles all network connections. If several wired communicationsnetworks 10 are present, one or more service interfaces 30 may beprovided to handle wired network connectivity. The service interface 30connects to an interprocess communication manager 26. The interprocesscommunication manager 28 manages all inter-process message routingwithin the remote network controller 20. One or more mobile interfaces24 may also be provided to handle connectivity with the radioinfrastructure(s) 56. Each mobile interface 24 is also connected to theinterprocess communication manager 28. The control process module 26 ofthe remote network controller 20 is provided to process managementfunctions and data integrity. The control process module 26 is connectedto the interprocess communication manager 28 and the console interface34. The console interface 34 allows for user configuration and reportingof data.

As further illustrated in FIG. 2, the remote network controller 20 maybe connected to a host data controller 22. One or more host datacontrollers 22 may be provided for connecting the remote networkcontroller 20 to specific radio infrastructures 56, e.g., a Motorolatrunked radio. The host data controller 22 may be connected to themobile interface 24 of the remote network controller 20.

In the field, the remote device 52 is connected to the mobile datacontroller 54 which, in turn, is connected to the radio infrastructure56 for transmitting and receiving data. The mobile data controller 54 isresponsible for connecting the remote device 52 to the radioinfrastructure 56 and to provide protocol-independent asynchronousserial data transfer to and from the remote device 52.

In order to provide transparent data transportation, whereby the networkprotocols and the protocols of the radio infrastructure 56 aretransparent or invisible to the user, inbound asynchronous data from theremote device 52 is collected and transported to the wired communicationnetwork 10 in packets over the radio infrastructure 56. The data is sentusing the existing protocols of the radio infrastructure 56. The remotenetwork controller 20 accepts the data and encapsulates it into theappropriate protocol used by the wired communication network 10. Thedata is passed to the wired communication network 10 in a similarfashion for passing data from any of the other locally-attached devices12. Similarly, outbound data to the remote device 52 from the wiredcommunication network 10 is removed from the network protocol by theremote network controller 20. The remote network controller 20 thenencapsulates the data into the appropriate protocol associated with theradio infrastructure 56 and sends the data over the radio infrastructure56 to the mobile data controller 54. Upon receipt of the data, themobile data controller 54 removes the data from the radio infrastructureprotocol and asynchronously sends the data to the remote device 52.

In accordance with the present invention, multiple wired networks 10with different protocols may be linked to multiple RF environments inany combination by incorporating the remote network controller andmobile data controller of the present invention.

FIG. 3 is a high-level flow chart for transporting outbound data fromthe wired communication network 10 to the remote device 52. As shown inFIG. 3, when data is to be sent to the remote device 52, the serviceinterface 30 of the remote network controller 20 accepts data from thewired communication network 10 at step 500. The service interface 30then converts the data from the protocol used by the wired communicationnetwork 10 and encapsulates it into an internal protocol used by theremote network controller 20 at step 502. In addition, the serviceinterface 30 may receive routing information from the wiredcommunication network 10 as to what remote device 52 the data is to bepassed, e.g., a network address or device identifier of the remotedevice 52.

At step 504, the service interface 30 forwards the data to theinterprocess communication manager 28. The interprocess communicationmanager 28 accepts the data at step 506 and, at step 508, places thedata in a queue for the appropriate destination mobile interface 24. Thedestination mobile interface 24 may depend on the radio infrastructure56 employed by the user. The outbound data that is to be passed from theinterprocess communications manager 28 to the mobile interface 24 may beencapsulated in an internal protocol of the remote network controller20, along with routing information to specify the remote device 52 towhich the data is to be sent. At step 510, the interprocesscommunication manager 28 notifies the mobile interface 24 that the datato be sent to the remote device 52 is queued for the mobile interface.The particular mobile interface 24 that the data is queued for dependson the particular radio infrastructure 56 employed to communicate withthe destination remote device 52. At step 512, the mobile interface 24requests that the queued data be sent from the interprocesscommunication manager 28. The mobile interface 24 may request data whenit is free to send the data to a destination remote device 52 and nothandling another process. At step 514, the mobile interface 24 acceptsthe queued data from the interprocess communication manager 28.Thereafter, at step 516, the mobile interface 24 determines, based onthe queued data, the destination node address of the remote device 52 towhich the data is to be sent. At step 518, the mobile interface 24forwards the data to the appropriate host data controller 22 so that itmay be sent over the radio infrastructure 56 at step 520. According toan aspect of the present invention, the host data controller 22 mayreceive the data, remove it from the internal protocol and encapsulatethe data into a packet determined by the protocol used by the radioinfrastructure 56. The packet of data may be broadcasted over the radioinfrastructure 56 so as to enable the host data controller 22 tocommunicate with multiple mobile data controllers 54 simultaneously. Thebroadcasted data packet may include the identification of the specificmobile data controller 54 to which the packet is to be delivered, sothat only uniquely identified mobile controller(s) may accept thepacket.

Referring again to FIG. 3, at step 522, the mobile data controller 54receives the data from the remote radio infrastructure 56 and decodesthe data. The data packet, once received by the mobile data controller54, is accepted and the data is removed from the packet. At step 524,the mobile data controller 54 validates the data and, at step 526, sendsan acknowledgment or rejection message to the host data controller 22via the radio infrastructure 56. According to the present invention, theremote network controller 20 and the host data controller 22 may beresponsible for ensuring the integrity of the data transported over theradio infrastructure. As such, an error detection/retry mechanism may beemployed to detect and correct data transmission errors. After theintegrity of the data is verified, the mobile data controller 54 at step528 will forward the data to the remote device 52. The data may beasynchronously transferred to the remote device 52 through a serialconnection.

FIG. 4 is a high-level flow chart illustrating the processing of inbounddata from the remote device 52 to the wired communication network 10. Atstep 550, the mobile data controller 54 accepts data from the remotedevice 52. At step 552, the mobile data controller 54 formats and sendsthe data to the remote network controller 20 via the radioinfrastructure 56, which may comprise a modem. The data may betransmitted using the appropriate protocol of the radio infrastructure56. The data may be modulated within the mobile data controller 54 priorto transmission via the radio infrastructure 56. The mobile datacontroller 52 may place the data from the remote device 52 into packetsto be sent over the radio infrastructure 56. The packet size can bedetermined by one of three methods. The first is a maximum packet size.Once an upper limit of data is accumulated, the mobile data controller54 may send the packet of information to the host data controller 22.For example, once 256 bytes of data are collected, the data may be sentby the radio infrastructure 56 over the RF communications link 55. Thesecond method is a maximum time to wait before sending data. In thiscase the mobile data controller 54 will send a packet after waiting apredetermined period of time, no matter how much data is accumulated.The third method involves the mobile data controller 54 detecting apredefined “end-of-packet” character which causes all accumulated datato be transmitted.

At step 554, the host data controller 22 receives and decodes the datapacket from the protocol of the radio infrastructure 56. Generally, thedata arrives as a packet of a predetermined size. At step 556, the hostdata controller 22 validates the data and, thereafter, sends at step 558an acknowledgment or rejection message to the mobile data controller 54based on the validation process. According to an aspect of the presentinvention, the host data controller 22 may determine if the transmitteddata packet is correct, or in error. The host data controller 22 mayalso determine if the data packet has arrived in the proper sequence,and that the packet is not a duplicate. As discussed above, the inbounddata may be removed from the packet and encapsulated in the internalprotocol used by the remote network controller 20. The internal protocolmay contain additional information, such as the identification of themobile data controller 54 which sent the information.

At step 560, the host data controller 22 forwards the data to the mobileinterface 24. The mobile interface 24 accepts the data from the hostdata controller 22 at step 562. The mobile interface 24 validates theaddress of the source of the data (e.g., the particular mobile datacontroller 54 or remote device 52) at step 562. At step 566, the mobileinterface 24 forwards the data to the interprocess communication manager28, which accepts the data at step 568. The mobile interface may alsopass the routing information specifying the remote device 52 from whichthe data originated. At step 570, the interprocess communication manager28 places the data into a queue for the destination service interface30. The particular destination service interface 30 will depend uponwhich wired communication network 10 the data is to be delivered.Included in the information which is passed to the service interface 30is the destination address (i.e., the communication network 10 to whichthe data is to be delivered). At step 572, the service interface 30,when available to handle data, requests the data from the interprocesscommunication manager 28. The service interface 30 accepts the data atstep 576 and converts the data into an appropriate form, i.e., protocol,usable by the wired communication network 10 at step 578. As a result,the data may be passed to the hardware device (e.g., an Ethernetcontroller) using the protocol required by the wired communicationnetwork 10. This configuration allows any existing network interfacecard to be used in conjunction with the remote network controller 20,because the data is placed into the appropriate network protocol by theservice interface 30 before it is transmitted to the wired network. Atstep 580, the service interface 30 forwards the data to the wiredcommunication network 10.

The validation process of the outbound data depicted in FIG. 3 andinbound data depicted in FIG. 4 does not depend on the type of wiredcommunication network 10 employed by the user. Through a singlevalidation process performed by the host data controller 22 and themobile data controller 54 (see steps 524 and 526 in FIG. 3 and steps 556and 558 in FIG. 4), the integrity of the data transmitted from the wiredcommunication network 10 to the remote device 52 through the radioinfrastructure 56 is ensured. This validation process may include, forexample, an error detection and retry mechanism to detect errors and tocause (when necessary) the retransmission of the data.

Referring now to FIG. 5, there is illustrated a block diagram of thebasic components of the mobile interface 24 of the remote networkcontroller 20 of the present invention. As noted above, the mobileinterface 24 is responsible for interfacing the remote networkcontroller 20 with the host data controller 22 and the radioinfrastructure 56. The mobile interface 24 may be a software interfacethat records statistical information related to inbound and outbounddata. The mobile interface 24 may also be responsible for errordetection and correction, and establishing and managing the mobile datasessions with the remote devices 52. The number of mobile interfaces 24provided in the remote network controller 20 depends on the number ofdifferent types of radio infrastructures 56 employed by the user. Eachtype of radio infrastructure 56 may have its own associated mobileinterface 24.

As shown in FIG. 5, the mobile interface 24 may include an event handlerand multithreading dispatcher 60, a process initialization module 62, amobile session manager 64, an inbound data event handler 66, an outbounddata event handler 68, a process termination module 70 and a host datacontroller interface module 72. The event handler and multithreadingdispatcher 60 may contain high-level logic and be used to control theoverall execution flow of the mobile interface 24. The processinitialization module 62 may be utilized to acquire resources andestablish the operation environment for the mobile interface 24 process.The process initialization module 62 may also be provided to initializethe host data controller 22.

According to the present invention, the mobile session manager 64 may beprovided to control the communications environment between the mobiledata controller 54 and the host data controller 22. The inbound dataevent handler 66 responds to signals from the host data controller 22indicating that inbound data is available and preprocess session controlinformation. The outbound data event handler 68 is provided to respondto signals from the interprocess communication manager 28 indicatingthat outbound data is available or that a session control function isrequired. The process termination module 70 functions to releasepreviously-acquired resources and terminate the mobile interface 24process efficiently. The host data controller interface module 72handles low-level interaction with the associated host datacontroller(s) 22.

The process flow of the event handler and multithreading dispatcher 60will now be described with reference to FIG. 6. At step 600, the processbegins when the remote network controller 20 is powered up andinitialized. At step 602, the process initialization module 62 isinvoked (described below with reference to FIG. 7). At step 604, theevent handler and multithreading dispatcher 60 waits for an event (e.g.,receipt of inbound data) to occur. While the event handler andmultithreading dispatcher 60 waits for an event to occur, mobileinterface 24 may be placed in a “sleep” mode to conserve processorresources. At step 606, once an event occurs, the event handler andmultithreading dispatcher 60 determines if it is a recognized event. Ifthe event handler and multithreading dispatcher 60 determines it is nota recognized event at step 606, processing returns to step 604. If,however, the event handler and multithreading dispatcher 60 determinesthat the event is a recognized event at step 606, then processingcontinues at step 608, where the event handler and multithreadingdispatcher 60 determines if the data was received from the host datacontroller 22.

At step 608, if the event handler and multithreading dispatcher 60determines the data was received from the host data controller 22, theevent handler and multithreading dispatcher 60 invokes the inbound dataevent handler 66, at step 614 (described below with reference to FIG. 9)and processing continues at step 604. If at step 608 the event handlerand multithreading dispatcher 60 determines that the data was notreceived from the host data controller 22, then the event handler andmultithreading dispatcher 60 determines whether the data was receivedfrom the service interface 30 at step 610.

If the event handler and multithreading dispatcher 60 at step 610determines that the data was received from the service interface 30,then at step 616 the outbound data event handler 68 is invoked(described below with reference to FIG. 10) and processing returns tostep 604. If the event handler and multithreading dispatcher 60 at step610 determines that the data was not received from the service interface30, then at step 612 the event handler and multithreading dispatcher 60determines if there is a process termination request.

If, at step 612, the event handler and multithreading dispatcher 60determines there is a process termination request, then at step 618, theprocess termination module 70 is invoked (described below with referenceto FIG. 11). If, at step 612, the event handler and multithreadingdispatcher 60 determines that there is not process termination request,then processing continues at step 604 to wait for another event.

Referring now to FIG. 7, there is illustrated an exemplary flow chartfor indicating the process flow of the process initialization module 62of FIG. 5. At step 620, the interprocess communications interface issetup. At step 622, the operating environment parameters are parsed andprocessed. This includes the host data controller 22 parametersreferenced in steps 626, 632 and 634 below. At step 624, memory isallocated for the session and other tables contained within the mobileinterface 24, which are used to control data flow and other operations.At step 626, the host data controller 22 parameters are accessed. Atstep 628, a path to the host data controller 22 port is opened. At step630, the host data controller 22 then is prevented from monitoring foran event from the remote device(s) 52. Step 630 prevents erroneoustransmissions that may arise if the host data controller 22 attempts tomonitor a remote device 52 before the initialization process iscomplete. At step 632, the host data controller 22 communicationparameters are set. At step 634, the communication parameters aredownloaded to the host data controller 22. After the initializationprocesses of steps 632 and 634 are completed, the host data controller22 at step 636 is enabled to monitor the remote device(s) 52. At step638, the entire initialization procedure is complete and processingreturns to step 604 in FIG. 6.

Referring now to FIG. 8, there is illustrated an exemplary flow chartdescribing the logic flow of the mobile session manager 64 of FIG. 5. Atstep 640, the mobile session manager 64 handler is entered from theevent handler and multithreading dispatcher 24 when remote data isdetected. At step 642, the remote identifier of the remote device 52 islooked up in a session table. At step 644, the mobile session manager 64determines if the remote identifier was found in the session table. Ifthe mobile session manager 64 determines that the remote identifier wasfound, the address is returned from the session table at step 646.

If the mobile session manager 64 does not find the remote identifier atstep 644, then at step 648 the mobile session manager 64 attempts toauthenticate the remote identifier. At step 650, the mobile sessionmanager determines if the authentication is successful. If at step 650the authentication is successful, then at step 656 the host datacontroller 22 is instructed to connect to the remote device 52 based onthe remote identifier. After the host data controller 22 is connected tothe remote device 52, the appropriate service interface 30 is invoked atstep 658. At step 660, processing is complete. If at step 650, theauthentication was not successful, the remote data is ignored at step652, and a null session table entry address is returned by the mobilesession manager 64.

Referring now to FIG. 9, there is illustrated an exemplary flow chart ofthe processing steps of the inbound data event handler 66 of FIG. 5. Atstep 662, the inbound data event handler is invoked (from step 614 inFIG. 6). At step 664, the remote identifier of the remote device 52 ischecked against the session table. At step 666, it is determined whetherthe inbound data event handler 66 found the remote identifier in thesession table. If at step 666, the remote identifier is not found in thesession table, the data is ignored and processing continues at step 604in FIG. 6. If the remote identifier is found in the session table atstep 666, the data is sent to the service interface 30 at step 670.Processing then continues at step 604 in FIG. 6.

Referring now to FIG. 10, there is illustrated an exemplary flow chartof the processing steps of the outbound data event handler 68 of FIG. 5.At step 672, the outbound data event handler is invoked (from step 616,FIG. 6). At step 674, the session table is checked for the outbound dataremote identifier. At step 676, it is determined if the outbound dataevent handler 68 found the remote identifier in the session table. If atstep 676, the remote identifier is not found in the session table, anerror is logged and the data message is ignored. Processing thencontinues at step 604 in FIG. 6. If the remote identifier is found inthe session table at step 676, the data is sent to the remote device 52as a single packet at step 680. Processing then continues at step 604 inFIG. 6.

Referring now to FIG. 11, there is illustrated an exemplary flow chartof the processing steps of the process termination module 70 of FIG. 5.At step 682, the process termination module 70 is invoked (from step 618in FIG. 6). At step 684, the process termination module 70 determines ifthere are any active remote sessions. If, at step 684, it is determinedby the process termination module 70 that there are no active sessions,then at step 686 all files are closed and the mobile interface 24terminates. If, however, it is determined by the process terminationmodule 70 that there are active sessions, then at step 688 all of theactive sessions are issued a disconnect request. At step 690, theprocess termination module waits for all active sessions to terminate.Once all active sessions have terminated at step 690, then all files areclosed and the mobile interface 24 terminates at step 686.

Referring now to FIG. 12, there is illustrated an exemplary flow chartof the processes associated with the host data controller interfacemodule 72 of FIG. 5. The host data controller interface module 72consists of a number of discrete functions (e.g., Initialize, Command,Send Data, and Receive Data) which are called when needed by the mobileinterface 24 and share common information about the host data controller22. The host data controller interface module 72 may access the hostdata controller 22 via a serial communications port which is assigned tothe mobile interface 24 and remains fixed when the remote networkcontroller 20 is in operation.

A host data controller 22 initialize routine begins at step 692. Theinitialization routine may be initiated in accordance with step 602 (seeFIG. 6) and steps 632 and 634 (see FIG. 7). At step 694, the serialcommunications port is accessed and setup. Thereafter, at step 696, theport handle and status is saved to be used by other processes within thehost data controller interface module 72.

A host data controller 22 command routine begins at step 698. Thecommand routine may be initiated upon the occurrence of a recognizedevent (see, e.g., step 604 in FIG. 6) so that the appropriate control oroperation commands may be sent to the host data controller 22. At step700, the host data controller 22 is placed into a command mode. At step702, a command (e.g., disconnect or receive) is issued to the host datacontroller 22 based on the event that is recognized. At step 704, thehost data controller interface module 72 awaits a confirmation ofacceptance of the command from the host data controller 22. At step 706,the result of the command is returned to the host data controllerinterface module 72.

A host data controller 22 send data routine begins at step 708 and maybe initiated from step 680 in FIG. 10. The send data routine isinitialized so that data may be sent to the appropriate remote device52. First, the physical identification of the remote device 52 isdetermined at step 710. Thereafter, the data to be sent to the remotedevice 52 is placed into a packet at step 712, and sent to the host datacontroller 22 at step 714.

At step 716, a host data controller 22 receive data routine is initiatedin accordance with step 670 in FIG. 9. The receive data routine isinitiated so that data from the remote device 52 may be received by theremote network controller 20. At step 718, data is accumulated withinthe host data controller 22 receive data routine (see, FIG. 12, step716) until a full packet of information is received. Thereafter, at step720, the packet is identified as either session oriented or monitororiented data. The identified data packet is then returned, at step 722,to the mobile interface 24 and sent to the wired communication network10 via the remote network controller 20.

Referring now to FIG. 13, in accordance with an aspect of the presentinvention, there is illustrated a block diagram of the basic componentsof the host data controller 22 (see, e.g., FIG. 2) of the presentinvention. The host controller 22 may be physically connected externalto the remote network controller 20 via the mobile interface 24. Thehost data controller 22 is specifically designed to convert the radioinfrastructure 56 protocol to the internal protocol of the remotenetwork controller 20. Typically, one host data controller 22 may beconnected to each mobile interface 24; however, one or more host datacontrollers 22 may be connected for redundancy and greater reliability.

As shown in FIG. 13, the host data controller 22 may comprise an RFcommunications interface module 80, a remote network controllercommunications interface module 78, and a configuration and monitoringmodule 82. The host data controller 22 may comprise any combination ofhardware and software to perform the functions described herein. Forexample, the host data controller 22 may comprise a commerciallyavailable processor or multi-processor with overlying applicationsoftware. The software running in the host data controller 22 may bewritten in Z80 or other appropriate high-level language (e.g., Pascal).The host data controller 22 may also contain a plurality of serial portsfor communicating with other devices.

The remote network controller communications interface module 78 isconnected to the mobile interface 24 of the remote network controller 20and is responsible for sending and receiving data to and from the remotenetwork controller 20. A subsystem port 76 (e.g., an RS-232 adapter) maybe used to connect the remote network controller communicationsinterface module 78 to the mobile interface 24 of the remote networkcontroller 20. If the host data controller 20 is connected to more thanone remote network controller, then additional subsystem portconnection(s) may also be provided to connect to the interface module 78to the additional remote network controllers. The remote networkcontroller communications interface module 78 sends health and statusinformation regarding the host data controller 22 to the mobileinterface 24. This information informs the remote network controller 20that the host data controller 22 is operational and accepting data.

The configuration and monitoring module 82 is specific to the type ofradio infrastructure 56 employed. Software parameters, such as thenumber of subsystem ports, how often to send health and status requests,and a list of mobile data controllers 54 to which the host datacontroller 22 can communicate, may be set and stored in theconfiguration and monitoring module 82. The configuration and monitoringmodule 82 can also accumulate statistics which are passed to the mobileinterface 24.

In order to diagnose potential system errors in the host data controller22, the remote network controller 20 may test and analyze the host datacontroller 22 over a diagnostic port (not shown) to determine a cause ofthe system failure or error. The diagnostic port may be used not only todetermine if the host data controller 22 is operational, but also toconfigure software parameters particular to the type of radioinfrastructure 56. These parameters can be changed to communicate with adifferent radio infrastructure 56 type as necessary.

The RF communications interface module 80 is responsible for sending andreceiving the radio-frequency transmissions. The RF communicationsinterface module 80 is specific to the radio infrastructure 56 in useand is connected to the radio infrastructure 56 by a communication line57. Again, because the host data controller 22 is designed to integratewith an existing radio infrastructure 56, each host data controller 22is software configured to work with many different types of radioinfrastructure 56 protocols for flexibility. The host data controller 22may be designed to be plugged into the remote network controller 20,connecting to the mobile interface 24, and can simply be exchanged witha different host data controller 22, or reprogrammed depending on theradio infrastructure 56 employed. Host data controllers 22 may beconfigured so as to be compatible with, for example, conventionalpoint-to-point radio systems, conventional repeater-based radio systems,LTR Trunking, Motorola Trunking, Ericsson (EDACS) Trunking—Voice Path,EDACS RDI Trunking—Data Path, and EDACS IMC Voice Path radioinfrastructures.

Referring to FIG. 14, there is illustrated a block diagram of thecomponents comprising the service interface 30 (see FIG. 2) of thepresent invention. The service interface 30 is responsible forcommunicating to and from the wired communication network 10. Theservice interface 30 is concerned only with the software level protocolsof the wired communication network 10. The hardware interface to thewired communication network 10 is accomplished by a known networkcontrol card, such as an Ethernet controller or a Token-Ring controller.

The number of service interface 30 connections to the wiredcommunication network 10 is dictated by the type of wired communicationnetwork 10. If the wired communication network 10 uses asynchronous datatransfer, there will be one service interface 30 for every entry point,e.g., serial port, into the wired communication network 10. In a localarea network (LAN) environment, each service interface 30 may handle avariety of different network addresses. A different service interface 30may be used for each type of wired communication network 10.

As shown in FIG. 14, the service interface 30 may include an eventhandler and multithreading dispatcher 90, a process initializationmodule 92, an inbound data event handler 94, an outbound data eventhandler 96, a process termination module 98 and a wired networkinterface module 100. The event handler and multithreading dispatcher 90may contain high-level logic and be used to control the overallexecution flow of the service interface 30. The process initializationmodule 92 acquires resources and establishes the operation environmentof the service interface 30 process. The inbound data event handler 94responds to signals from the interprocess communication manager 28 thatinbound data is available and preprocess session control information.The inbound data event handler 94 may also handle asynchronous timerevents. The outbound data event handler 96 is provided to respond tosignals from wired communication network interface module 100 thatoutbound data is available or that a timer event has occurred. Theprocess termination module 98 functions to release previously-acquiredresources and terminate the service interface 30 process gracefully. Thewired communication network interface module 100 handles low-levelinteraction with the associated wired communication network transportmechanism, i.e., communication protocol, being used.

An exemplary process flow of the event handler and multithreadingdispatcher 90 (see FIG. 14) of the present invention will now bedescribed with reference to FIG. 15. At step 800, the process beginswhen the service interface 30 is powered up and initialized. At step802, the process initialization module 92 is invoked (described belowwith reference to FIG. 16). At step 804, the event handler andmultithreading dispatcher 90 waits for an event to occur in response,e.g., to network or remote device activity. While the event handler andmultithreading dispatcher 90 waits for an event to occur, the serviceinterface 30 may be placed in a “sleep” mode to conserve processingpower. At step 806, once an event occurs, the event handler andmultithreading dispatcher 90 determines if it is a recognized event.Recognized events may include Initialize, Send Data, Receive Data and/orTerminate. If the event handler and multithreading dispatcher 60determines it is not a recognized event at step 806, then processingreturns to step 804. If the event handler and multithreading dispatcher90 recognizes the event at step 806, then processing continues at step808, where the event handler and multithreading dispatcher 90 determinesif the data was received from the host communication network 10.

At step 808, if the event handler and multithreading dispatcher 90determines the data was received from the host wired communicationnetwork 10, the event handler and multithreading dispatcher 90 invokesthe inbound data event handler 94, at step 814 (described below withreference to FIG. 17) and, thereafter, processing continues at step 804.If at step 808 the event handler and multithreading dispatcher 90determines that the data was not received from the host wiredcommunication network 10, the event handler and multithreadingdispatcher 90 then determines if the data was received from the mobileinterface 24 at step 810.

If the event handler and multithreading dispatcher 90 determines at step810 that the data was received from the mobile interface 24, then atstep 816 the outbound data event handler 96 is invoked (described belowwith reference to FIG. 18) and, thereafter, processing continues at step804. If the event handler and multithreading dispatcher 90 at step 810determines that the data was not received from the mobile interface 24,then at step 812 the event handler and multithreading dispatcher 90determines if there is a process termination request.

If, at step 812, the event handler and multithreading dispatcher 90determines there is a process termination request, then at step 818 theprocess termination module 98 is invoked (described below with referenceto FIG. 19). However, if at step 812 the event handler andmultithreading dispatcher 90 determines that there is not processtermination request, then processing returns to step 804 to wait foranother event.

Referring now to FIG. 16, there is illustrated an exemplary flow chartdescribing the process flow of the process initialization module 92(see, e.g., FIG. 14) of the present invention. At step 820, theinterprocess communications interface is setup when the serviceinterface 30 is started or powered up. At step 822, the operatingenvironment parameters are parsed and processed (i.e., the parameters ofthe operating environment are processed individually). At step 824, anyresources required (e.g., memory) are acquired. Thereafter, at step 826,the wired communication network interface module 100 is invoked (seeFIGS. 20-24 discussed below). As discussed below, the wiredcommunication network interface module 100 may include severalprocedures associated with initializing the connectivity with the wiredcommunication network 10, reading data from the wired communicationnetwork 10, writing data to the wired communication network 10, andterminating connectivity with the wired communication network 10. Inaccordance with an aspect of the present invention, a unique set ofprocedures may be provided by the wired communication network interfacemodule 100 for each type of wired communication network 10. For example,a unique set of procedures may be provided for networks utilizingtransparent asynchronous communications, TCP/IP stream sockets, VehicleLocation Reporting Facilities, Bidirectional Messaging Facilities, orCredit Card Verification Facilities.

After the wired communication network interface module 100 is invoked,the results of the previous operations performed at step 826 are sent atstep 828 to the mobile interface 24. At step 830, it is determined bythe process initialization module 92 if the wired communication networkinterface module 100 was successfully invoked at step 826. If it isdetermined at step 830 that the wired communication network interfacemodule 100 was successfully invoked, then the initialization is completeat step 832, and processing returns to step 804 in FIG. 15. If, however,it is determined at step 830 that the wired communication networkinterface module was not successfully invoked, then the serviceinterface 30 is terminated at step 834.

Referring now to FIG. 17, there is illustrated an exemplary flow chartof the processing steps for the inbound data event handler 94 (see,e.g., FIG. 14) of the present invention. At step 836, the inbound dataevent handler is invoked (from step 814 in FIG. 15). At step 838, thedata portion of the message sent by the wired communication network 10is extracted. At step 840, the service interface 30 requests a packet ofdata from the mobile interface 24. At step 842, after the packet isaccepted by the service interface 30, data is sent to the appropriatedestination via the wired communication network 10. The inbound dataevent handler 94 then waits for a disconnect request at step 844. If theinbound data event handler 94 receives a disconnect request at step 844,then a disconnect command is sent to the mobile interface 24 at step846. Processing then continues at step 804 in FIG. 15. If, however, theinbound data event handler 94 does not receive a disconnect request atstep 844, then the request received is ignored at step 848 and,thereafter, processing then continues at step 804 in FIG. 15.

Referring now to FIG. 18, there is illustrated an exemplary flow chartof the processing steps for the outbound data event handler 96 (see FIG.14) of the present invention. At step 850, the outbound data eventhandler is invoked (from step 816 in FIG. 15). At step 852, the outbounddata event handler 96 determines if there is a request (e.g., adisconnect request from the wired communication network 10 or the remotedevice 52). If there is a request, then processing continues at step856. However, if there is presently not a request, then at step 854 theoutbound data from the network 10 is sent to remote device 52 via themobile interface 24. At step 865, the outbound data event handler 96then determines if a disconnect request has been received. If theoutbound data event handler 96 receives a disconnect request at step856, then a disconnect command is sent to the mobile interface 24 atstep 860 by the interprocess communication manager 28 (see, e.g., FIG.2). Processing then continues at step 804 in FIG. 15. If, however, theoutbound data event handler 96 does not receive a disconnect request atstep 856, then the request received is ignored at step 862 andprocessing then continues at step 804 in FIG. 15.

Referring now to FIG. 19, there is illustrated an exemplary flow chartof the processing steps for the process termination module 98 (see FIG.14) of the present invention. At step 864, the process terminationmodule 98 is invoked (from step 818 in FIG. 15). At step 866, the wiredcommunication network interface module 100 connection is closed.Thereafter, at step 868, the processes associated with the serviceinterface 30 are terminated.

Referring now to FIGS. 20-24, there are illustrated exemplary flowcharts of the various processes that may be performed by the wiredcommunication network interface module 100 of the present invention. Thewired communication network interface module 100 may consist of a numberof discrete functions which provide the service interface 30 with auniform means of communicating with various host computer networks,irrespective of the communication protocols of the wired communicationnetwork 10. All protocol and other feature-specific communicationstranslation and handling is performed at the wired communication networkinterface module 100. The wired communication network interface module100 may be designed for networks utilizing different implementations,such as transparent asynchronous communication, Hayes compatiblecommunication, TCP/IP stream socket, Bidirectional Messaging Facilities,File Transfer Facilities, SNA Protocol Enveloping, Vehicle LocationReporting Facilities, Credit Card Verification Facilities, and HarrisDNP 3.0 Frame Relay. As noted above, a unique set of procedures may beprovided by the wired communication network interface module 100 foreach type of wired communication network 10. Examples of several ofthese sets of procedures are provided below.

Referring now to FIG. 20, there is illustrated an exemplary flow chartof the set of procedures associated with the wired communication networkinterface module 100 that are designed for transparent asynchronouscommunication networks. At step 900, an initialization process begins inaccordance, for example, with step 802 of FIG. 15. At step 902, theserial port of the wired communication network 10 that is to be used isdetermined, and the identified port is opened or accessed at step 904.At step 906, the speed (bps), the parity (odd or even), and the databits for communication with the network 10 are established along withother appropriate parameters.

At step 908 a data read operation begins. The data read routine may beinvoked by the outbound data event handler 96 at step 850 (see FIG. 18).Initially, at step 910, the wired communication network interface module100 determines if there is data to be read from the serial port. If atstep 910 the wired communication network interface module 100 determinesthere is data to be read, then at step 916 the data is added to anaccumulated data buffer within the remote network controller 20. At step918, if the wired communication network interface module 100 determinesthat the data buffer is full, then at step 914 the data accumulated inthe buffer is returned to the calling module. If, however, at step 910the wired communication network interface module 100 determines there isno data to be read from the serial port attached to the network 10, thenat step 912 it is determined if the inter-character time (e.g., apredetermined character receipt delay time) has been exceeded. If atstep 912 the inter-character time has been exceeded, then at step 914the accumulated data buffer is returned to the calling module to befurther processed. Otherwise, if the inter-character time has not beenexceeded, then processing continues at step 910 so that the wiredcommunication network interface module 100 may again determine if thereis data to be read from the serial port.

At step 920, a write data routine is started. The write data routine maybe initiated by the inbound data event handler 94 at step 836 in FIG.17. At step 922, the data is sent directly to the serial port of thewired communication network 10. The write data routine is thereaftercompleted.

At step 924, a terminate routine is initiated. The terminate routine maybe initiated in accordance with a terminate request at step 818 in FIG.15. In response to initiation of the terminate routine, the serial portof the network 10 is closed at step 926. Thereafter, at step 928, theserial port resource is released so it may be used by another process.Finally, at step 930, any data buffers in use are also released.

Referring now to FIG. 21, there is illustrated exemplary flow charts ofthe set of procedures associated with the wired communication networkinterface module 100 for networks utilizing TCP/IP stream socketconnectivity. At step 932, an initialization process begins inaccordance, for example, with step 802 of FIG. 15. At step 934, a hostnetwork and serial port to be used are determined. At step 936, anappropriate socket is created. At step 938, the socket server isaccessed for data transport.

At step 940 a data read operation begins. The data read routine may beinvoked the outbound data event handler 96 at step 850 (see FIG. 18).Initially, at step 942, the wired communication network interface module100 determines if there is data to be read from the socket. If at step942 the wired communication network interface module 100 determinesthere is data to be read, then at step 944 the data buffer is returnedto the remote network controller 20 for further processing.

At step 946, a write data routine is started. The write data routine maybe initiated by the inbound data event handler 94 at step 836 in FIG.17. At step 948, the data is sent by the wired network interface module100 directly to the socket at the wired communication network 10. Thewrite data routine is thereafter completed.

At step 950, a terminate routine is initiated. The terminate routine maybe initiated in accordance with a terminate request at step 818 in FIG.15. Initially, the socket is closed at step 952. Thereafter, at step954, the socket resource is released so it may be used by anotherprocess. Finally, at step 956, any data buffers in use are alsoreleased.

Referring now to FIG. 22, there is illustrated exemplary flow charts ofthe set of procedures associated with the wired communication networkinterface module 100 for use with networks utilizing Vehicle LocationReporting Facilities. At step 958, an initialization process begins inaccordance, for example, with step 802 of FIG. 15. At step 960 the wiredcommunication network interface module 100 determines a positionrecording file to be used to record data. The position recording filemay be stored within the wired communication network 10. At step 962,the position recording file is accessed from the network 10. Thereafter,at step 964, the recording interval is placed into a read buffer thatmay be provided to the remote device 52 via the mobile data controller54.

At step 966 a data read operation begins. The data read routine may beinvoked by the outbound data event handler 96 at step 850 (see FIG. 18).Initially, at step 968, the wired communication network interface module100 determines if there is data in the read buffer. If at step 968 thewired communication network interface module 100 determines there isdata in the read buffer, then at step 970 the contents of the readbuffer is returned to the calling module.

At step 972, a write data operation is started. The write data routinemay be initiated by the inbound data event handler 94 at step 836 inFIG. 17. Initially, at step 974, the wired communication networkinterface module 100 determines if a full Global Positioning Satellite(GPS) message has been accumulated. If at step 974, the wiredcommunication network interface module 100 determines that a full GPSmessage has not been accumulated, then no action is taken at step 980.If at step 974, the wired communication network interface module 100determines that a full GPS message has been accumulated, then themessage is converted at step 976 to a standard form usable by the wiredcommunications network 10. At step 978, the position recording file atthe host is appended with the GPS message.

At step 982, a terminate routine is initiated. The terminate routine maybe initiated in accordance with a terminate request at step 818 in FIG.15. The terminate routine may comprise closing the position recordingfile at step 984.

Referring now to FIGS. 23A and 23B, there is illustrated exemplary flowcharts of the set of procedures associated with the wired communicationnetwork interface module 100 that are designed for networks utilizingBidirectional Messaging Facilities or Store and Forward MessagingFacilities. Referring to FIG. 23A, at step 986, an initializationprocess begins. The initialization process may be started in accordance,for example, with step 802 of FIG. 15. At step 988, a message queue forthe remote device 52 is accessed. Thereafter, at step 990, if no queueexists for the remote device 52, a message queue is created at theremote network controller 20.

At step 992 a data read operation begins. The data read routine may beinvoked by the outbound data event handler 96 at step 850 (see FIG. 18).Initially, at step 994, the wired communication network interface module100 determines if a message is in the process of being sent. If at step994 the wired communication network interface module 100 determines thata message is being sent, then at step 998, the current message segmentis sent by the remote device 52 to the wired communication network 10.If at step 994 the wired communication network interface module 100determines that no message is being sent, then at step 996, the wiredcommunication network interface module 100 determines if there is amessage queued. If at step 996 the wired communication network interfacemodule 100 determines that no messages are queued then no action istaken. However, if at step 996 the wired communication network interfacemodule 100 determines that there is a message queued for the remotedevice 52, then the current message queued is sent at step 998. Afterthe last segment of the message is sent, the wired communication networkinterface module 100 may indicate that delivery of the message ispending to the remote device 52 at step 1000.

At step 1002, a write data routine is initiated. The write data routinemay be initiated by the inbound data event handler 94 at step 836 inFIG. 17. Initially, at step 1004, the wired communication networkinterface module 100 determines if a new message is present. If at step1004 the wired communication network interface module 100 determinesthat a new message is present, then at step 1010 the wired communicationnetwork interface module 100 starts a new queue entry. Thereafter,processing continues at step 1006, where the message segment isrecorded. At step 1008, the wired communication network interface module100 determines if this is the last segment. If at step 1008 the wiredcommunication network interface module 100 determines that it is thelast segment, then at step 1012, the queue entry is closed and “MessageReceived” message may be placed into the read buffer at step 1014 to besent to the remote device 52. If at step 1008, the wired communicationnetwork interface module 100 determines that it is not the last segment,then no action is taken.

Referring to FIG. 23B, at step 1016, a terminate routine is started. Theterminate routine may be initiated in accordance with a terminaterequest at step 818 in FIG. 15. At step 1018, the wired communicationnetwork interface module 100 determines if the terminate request hascome in the middle of a message. If at step 1018, the wiredcommunication network interface module 100 determines that the requestcame in the middle of a message, then the message is purged at step1022. Processing then continues at step 1020, where the wiredcommunication network interface module 100 closes the message queue.

Referring now to FIG. 24, there is illustrated flow charts of the set ofprocedures associated with the wired communication network interfacemodule 100 designed for use with networks utilizing Credit CardPoint-of-Sale Facilities. At step 1024, an initialization processbegins. The initialization process may be started in accordance, forexample, with step 802 of FIG. 15. In accordance with the invention, noaction is required for the initialization procedure.

At step 1026 a data read operation begins. The data read routine may beinvoked the outbound data event handler 96 at step 850 (see FIG. 18).Initially, at step 1028, the wired communication network interfacemodule 100 determines if there is a response from a server attached tothe wired communication network 10. If at step 1028 the wiredcommunication network interface module 100 determines there is aresponse from the server, then at step 1030 the response is read, andthe response buffer is returned to the remote device 52 at step 1032. Ifat step 1028 there is no response from the server, then no action istaken.

At step 1034, a write data operation is started. The write data routinemay be initiated by the inbound data event handler 94 at step 836 inFIG. 17. At step 1036, the wired communication network interface module100 first determines if a full request by the remote device 52 has beenaccumulated. If at step 1036 the wired communication network interfacemodule 100 determines that a full request has not been accumulated, thenthe remote device 52 continues to accumulate a request at step 1042. Ifat step 1036 a full request has been accumulated, then at step 1038, therequest is formatted for the server on the wired communications network10. Thereafter, the request is placed into the server file at step 1040.

At step 1044, a terminate routine is illustrated. The terminate routinemay be initiated in accordance with a terminate request at step 818 inFIG. 15. According to the present invention, no action is necessary forthe terminate routine.

Referring now to FIG. 25, there is illustrated a block diagram of thevarious components of the mobile data controller 54, according toanother aspect of the present invention. The mobile data controller 54may be specifically designed to match the asynchronous data transferredto and from the remote device 52 to the radio infrastructure 56protocol. Typically, there is one type of mobile data controller 54 thatis associated with a host data controller 22 which is connected to themobile interface 24 of the remote network controller 20. In addition,the mobile data controller 54 may have a unique identifier associatedwith it for routing purposes.

In accordance with the present invention, the mobile data controller 54may be implemented by any combination of hardware and software. Forexample, the mobile data controller 54 may comprise a commerciallyavailable processor with overlying software and random access memory.The software running in the mobile data controller 54 may be written inZ80 or other appropriate processor-based (i.e., native) assemblylanguage and configured to the specific radio infrastructure 56. Thesoftware may specify the various voltage levels and logic signalsnecessary to communicate via the RF communications infrastructure 56. Asnoted above, the mobile data controller 54 may translate and pass anyprotocols associated with the wired communications network 10 to andfrom the remote device 52 to make it appear to the wired communicationnetwork 10 that the remote device 52 is locally-attached.

The mobile data controller 54 is configurable over the radioinfrastructure 56. configuration information may be input by an operatorat the remote network controller 20 through the console interface 34(see FIG. 2) and passed over the radio infrastructure 56 to the mobiledata controller 54. This allows parameters such as packet size to bechanged at the host wired communications network 10 without thenecessity of altering the mobile data controller 52 in the field.

As shown in FIG. 25, the mobile data controller 54 may comprise an RFcommunications interface module 106, a remote device communicationsinterface module 102, and a configuration and monitoring module 104. Themobile data controller 54 may be connected to the remote device 52 via acommunication port 108 for sending and receiving data. The remote devicecommunications interface module 102 is connected to the remote device 52via the communication port 108 and is responsible for sending data to,and receiving data from, the remote device 52. The communication port108 may comprise, for example, an RS-232 adapter.

The configuration and monitoring module 104 is specific to the type ofradio infrastructure 56 employed. Software parameters, such as thenumber of subsystem ports, how often to send health and status requests,and a list of host data controllers 22 to which the mobile datacontroller 54 can communicate, may be set and stored in theconfiguration and monitoring module 104. The configuration andmonitoring module 104 can also accumulate statistics which are passed tothe host data controller 22.

In order to diagnose potential system errors in the mobile datacontroller 54, an operator may be provided with the ability to fieldtest and analyze the mobile data controller via an external diagnosticport 112 to determine a cause of the system error or failure. Thediagnostic port 112 may be used not only to determine if the mobile datacontroller 54 is operational, but also can be used to configure softwareparameters to determine the type of the radio infrastructure 56. Theseparameters can be changed to communicate with a different type of radioinfrastructure 56 as necessary.

The RF communications interface module 106 is responsible for sendingand receiving the data via radio-frequency (RF) transmission. The RFcommunications interface module 106 is specific to the radioinfrastructure 56 used, and is connected to the radio infrastructure 56through a communication line 110. Because the mobile data controller 54is designed to integrate with an existing radio infrastructure 56, eachmobile data controller 54 may be software configured, for purposes offlexibility, to work with many types of radio infrastructure 56protocols. The RF communications interface module 106 may also sendhealth and status information regarding the mobile data controller 54 tothe host data controller 22. This information may inform the remotenetwork controller 20 that the mobile data controller 54 is operationaland the remote device 52 is accepting data.

According to the present invention, the RF communication interfacemodule 106 may include a commercially available modem (not shown). Themodem may be selected depending on the data rate(s) of the communicationline 100 and the radio infrastructure 56. More than one modem may beprovided if multiple data rates are required. Optionally, the modem canbe implemented using a Digital Signal Processing (DSP) chip andassociated software. The DSP chip can be a commercially availableprogrammable signal processing chip. In such a case, the DSPimplementation will allow a single modem to be changed (e.g., byuploading new parameters to the DSP software) in order to communicatewith a plurality of different types of radio infrastructures 56 havingdistinct protocols and data rates.

Similar to the host data controllers 22, the mobile data controllers 54may be compatible with, for example, conventional point-to-point radiosystems, conventional repeater-based radio systems, LTR Trunking,Motorola Trunking, Ericsson (EDACS) Trunking-Voice Path, EDACS RDITrunking-Data Path, and EDACS IMC Voice Path based radio infrastructures56.

Referring again to FIG. 2, a brief description of the interprocesscommunications manager 28 will be provided. According to the presentinvention, the interprocess communications manager 28 is responsible forrouting all communication between the various modules and interfaceswithin the remote network controller 20. The interprocess communicationsmanager 28 creates a logical route from the remote device 52 to theservice interface 30 of the remote network controller. The interprocesscommunications manager 28 passes routing information which determinesfrom which radio infrastructure 56 and remote device 52 the inbound datahas come from, and to which radio infrastructure 56 and remote device 52the outbound data will be sent.

The interprocess communications manager 28 may also pass informationgenerated by the remote network controller 20, which is independent ofthe data and routing information. This information may include internalparameters and error detection codes. The interprocess communicationsmanager 28 also interfaces with the control process module 26. Thecontrol process 26 may act as the “central hub” of the remote networkcontroller 20. The control process 26 provides resource management,process management, session management, configuration management andsystem statistics management within the remote network controller 20.

As further shown in FIG. 2, the remote network controller 20 alsoincludes a console interface 34. The console interface 34 may be adaptedto allow a network operator to configure and control the wirelessNetwork Interfaces described above, the mobile user characteristics andthe configuration information of the wired communications network 10.The console interface 34 may be a stand-alone platform having acommercially available processor (e.g., an Intel or Motorola basedprocessor) and an Ethernet controller card for communicating, forexample, with another remote network controller 20.

Referring now to FIG. 26, there is illustrated a remote gateway 120, inaccordance with another aspect of the present invention. As shown inFIG. 26, the remote gateway 120 is comprised of a transparentcommunications module 122, a field service interface module 128, aconfiguration and health module 124 and a RF communications module 126.The remote gateway 120 is functionally similar to the mobile datacontroller 54. However, the remote gateway 120 is a specific type ofmobile data controller that may be used to attach to a remote telemetryunit for monitoring, for example, electrical power distribution.

The transparent communications module 122 is responsible forcommunicating with a terminal device, typically a Remote Telemetry Unit(RTU) located in the field, and accepts data from the RF communicationsmodule 126. As shown in FIG. 26, the transparent communications module122 may be connected to a RTU 133 via a communication line 130. Thetransparent communications module 122 does not recognize any protocol,but handles hardware flow control and buffering and packetizing. Datacommunication between the transparent communications module 122 and theRTU 133 may be carried through asynchronous serial transfer.

The RF communications module 126 is configured to communicate with theremote network controller 20 using whatever protocol is required fordata transport over the radio infrastructure 56. The RF communicationsinterface module 126 interfaces with the radio infrastructure 56 in asimilar manner as previously described above with regard to the RFcommunications interface module 106. The RF communications interfacemodule 126 accepts data from the transparent communications module 122and delivers it to the radio infrastructure 56 for transmission to theremote network controller. The RF communications interface module 126detects collisions with inbound RF data and restarts outboundtransmissions. The RF communications interface module 126 performserror/retry functions and notifies the transparent communications module122 of successes or failures.

The field service interface module 128 allows a technician to field testthe remote gateway 120 and troubleshoot the remote gateway should asystem error or problem arise. An external diagnostic port 112 connectedto the field service interface module 128 may be provided for thispurpose. The field service interface module 128 may interact with theconfiguration and health module 124 to query, set, and reset localconfiguration of the remote gateway 120.

The configuration and health module 124 may accept configurationinformation from the remote network controller 20 via the radioinfrastructure 56 and adjust the operating parameters of the remotegateway 120 accordingly. The configuration and health module 124 mayalso monitor and determine if the RF communications module 126 hassuccessfully transmitted a packet of information to the host datacontroller 22 by analyzing the data stream. If a packet of informationhas not been successfully transmitted, the configuration and healthmodule 124 may direct the RF communications module 126 to resend thepacket of information to the host data controller 22.

Referring now to FIGS. 27 and 28, there is illustrated a block diagramof an integrated remote network controller 140 according to anotheraspect of the present invention. The components of the remote networkcontroller 140 that are similar to that discussed above with respect toFIG. 2 are designated with the same reference numeral and also with aprime (“′”) added thereto.

As shown in FIG. 27, the remote network controller 140 according toanother aspect of the present invention may include one or more serviceinterfaces 30′, an interprocess communications manager 28′, a controlprocess 26′, one or more mobile interfaces 24′, and a subsystemsynchronization processor 150 which is used to link one or more remotenetwork controllers 140 together (see FIG. 28). As further shown in FIG.27, one or more host data controllers 22′ are connected to the mobileinterfaces 24′ and provided externally to the remote network controller140. The number of host data controllers 22′ and mobile interfaces 24′may be dependent on the number of radio infrastructures 56 present. Inaddition, the number of service interfaces 30′ may be dependent on thenumber and type of wired communications networks 10 present.

According to an aspect of the present invention, two remote networkcontrollers 140 may be linked by a local network 152 (see FIG. 28). Thisconfiguration provides a redundant system which insures greaterreliability of communication between the remote device 52 and the wiredcommunications network 10. For example, should any particular componentfail, such as a host controller 22′ or an interprocess communicationsmanager 28′, the remote device 52 can still communicate with the wiredcommunication network 10 because of the redundancy of the components ofthe remote network controllers 140 provided.

There are two main implementations of this system according to thepresent invention. With the first implementation, only one of the remotenetwork controllers 140 is operating at any given time. Should theoperational remote network controller 140 fail, the other remote networkcontroller 140 may immediately take its place. For example, if remotenetwork controller “A” fails, then remote network controller “B” may beactivated to take its place.

Under the second implementation, a distributed processing scheme isutilized and both of the remote network controllers 140 are operated atthe same time. According to the distributed processing scheme, theprocessing load (e.g., event handling and data transfer) may bedistributed among the operational remote network controllers 140. Shoulda particular remote network controller 140 (e.g., controller “B”) fail,the remaining operational remote network controller 140 (e.g.,controller “A”) will handle the entire processing load.

The above-mentioned distribution of the processing load is generally afunction of the radio infrastructure 56, and not the processing capacityof the remote network controllers 140. This is because performanceincreases are mainly based on the number of available communicationschannels, rather than the raw processing capability of the remotenetwork controllers 140 attached to the wired communications network 10.For example, if the radio infrastructure 56 is a trunking radio networkwith five channels, it is possible for all five channels to besimultaneously allocated and used by the remote network controllers 140.On the other hand, if there is only one channel available in the radioinfrastructure 56, then only one remote network controller 140 canaccess the radio infrastructure 56 at a time; as a result, noperformance gain may be realized by employing multiple remote networkcontrollers 140 when only limited channels are available.

As illustrated in FIG. 28, the local network 152 is used to connect theremote network controllers 140 together. The local network 152 may be,for example, an Ethernet local area network. Each of the remote networkcontrollers 140 includes a subsystem synchronization process module 150that is connected to the local network 152. Two separate consoleinterfaces 34′ may also be attached to the local network 152. Eachconsole interface 34′ may be attached to the local network 152 to allowan operator to configure and control a particular remote networkcontroller 140.

The subsystem synchronization process module 150 may be implementedthrough any combination of hardware and software and is responsible forkeeping track of all routing tables and health and status informationassociated with both of the remote network controllers 140. Eachsubsystem synchronization process module 150 is connected to aninterprocess communications manager 28′ of one of the remote networkcontrollers 140 and may access all routing tables and health and statusinformation with respect to the remote network controller from theinterprocess communications manager. The health and status informationand routing tables may be periodically updated based on the status ofand events present at the remote network controller 140. Theperiodically updated health and status information and routing tablesmay then be shared with the other subsystem synchronization processmodule 150 via the local network 152 so that the tables and informationassociated with both of the remote network controllers 140 is maintainedin each of the subsystem synchronization process modules 150. Since thetables and information are periodically updated, a synchronizationroutine may be provided so that the information and tables are sent tothe respective subsystem synchronization process modules 150 atpredetermined intervals. If a particular subsystem synchronizationprocess module 150 does not send or receive the tables and information,or if a particular subsystem synchronization process module 150 sendsinformation indicating that one of the remote network controllers 140has malfunctioned, the other subsystem synchronization process module150 may reroute any existing connections to the host data controllers22′ and to the wired network 10 of the malfunctioning remote networkcontroller 140 to the remaining operational remote network controller140.

As further shown in FIG. 28, the host data controllers 22′ have twoports, 154 and 156, that are connected to a different remote networkcontroller 140. As in FIG. 2, the remote network controller 140communicates to the host data controller 22′ and sends health and statusinformation through the ports. If the host data controller 22′ does notreceive information that one of the remote network controllers 140 isoperational, the host controller 22′ can switch ports, e.g., from port154 to port 156, in order to communicate with the other remote networkcontroller 140.

While the invention has been described with references to severalexemplary embodiments, it is understood that the words which have beenused herein are words of description and illustration, rather than wordsof limitation. Changes may be made, within the purview of the appendedclaims, without departing from the scope and spirit of the invention inits aspects.

For example, although FIG. 28 only shows two remote network controllers140 that are connected by a local network 152, it is possible to connecttwo or more remote network controllers by the local network 152 toprovide increased redundancy. In addition, a plurality of local networks152 may be provided to connect the remote network controllers. Othermodifications to the present invention may include selectivelyprocessing inbound and outbound data in a different logic order and/orby different components. In accordance with such a modification,processing functions may be performed only by the control process, or inthe interprocess communication manager. Another application may becombining the mobile interface with a host data controller, and placingthe integrated unit within the remote network controller.

Referring now to FIG. 29, therein is illustrated a general overview ofanother embodiment of the present invention which includes a mobileRouter 200 in accordance with an aspect of the present invention. TheRouter 200 provides the mobile application or device 52 with thecapability to selectively transmit and receive data over a plurality ofradio frequency infrastructures 56 and/or the public switched telephonenetwork 58 in accordance with user configured parameters.

Referring now to FIG. 30, therein is illustrated a schematic blockdiagram of the mobile Router 200. In the following description of theRouter 200, each of the elements will be initially generally describedand in greater detail thereafter. As shown in FIG. 30, the mobileapplication or device 52 may be attached to multiple Networks by theRouter 200 through Network Interfaces 214A-D, a Router Core 204, and aSwitch 212. The Network Interfaces 214A-D provide connectivity for databetween the Switch 212 and the various Networks infrastructures (e.g.,radio infrastructures 56 and public switch telephone network 58) throughwhich the mobile device or application 52 connects to the communicationsnetwork 10 (see FIG. 1). The Switch 212 is actuated by the Router Core204, and sends data to a fixed host application or device (e.g., RNC 20)via the selected network. The Network Interface 214 provides informationto the Network Availability process 210, which sends this information tothe Decision process 206. The Decision process 206 operates inaccordance with User Configured parameters 208 which specify when andthrough which Network the data is to be transmitted. The decisionprocess 206 monitors the User Configuration parameters 208, and theNetwork Availability 210. When the Decision process 206 (in accordancewith User Configuration 208 parameters) specifies that a Network (e.g.,Network 3) different than the Network currently in use (e.g., Network 1)should be used, the Decision process 206 checks the Network Availability210 for the particular Network to be switched to. If the Network isavailable, the Decision process 206 instructs the Router Core 204 toswitch to the new Network. The Router Core 204 then updates routingtables (not shown) maintained within the Router Core 204 to reflect thenew data path, and actuates the Switch 212 to connect to the newNetwork. Data may then flow over the new Network. In accordance with anaspect of the present invention, data may flow inbound to the fixed hostthrough one Network, and outbound to the remote mobile Application ordevice 52 through the same Network, or through a different Network.

With reference to FIG. 30, the mobile application or device 52 maycomprise a software application running on a portable or laptop computerperforming a variety of functions as programmed by the softwareapplication (e.g., database services). The Application or device 52 mayalso comprise a special purpose device designed to perform a particularfunction, such as a credit card reader or barcode scanner. TheApplication or device 52 may generate a data stream which is sent to afixed location (e.g., a host computer infrastructure 10).

An exemplary application running on the mobile device 52 is a mobileremote client application which provides the remote user with thecapability to send and retrieve data from a fixed database serverapplication. The data may consist of customer records which, forexample, may be used by service personnel operating a fleet of vehiclesto service customers scattered about a wide geographic area. In theexemplary application, the mobile client application may requestcustomer records from the fixed database server, and display the recordsfor viewing by mobile service personnel. The mobile client applicationmay send updated records to the fixed database as the service personnelfinish assigned tasks. The updated records may contain a servicehistory, equipment upgrades, and repairs for each customer.

Another exemplary application running on the mobile device 52 may be aclient application which retrieves a list of dispatched jobs to beperformed by the service personnel during each day. The jobs may beuploaded to the remote mobile device 52 each morning and stored inanother client application in the mobile device 52. As the servicepersonnel change job locations, the status of each job may be updated toindicate a status, e.g., en route, arrived and finished with comments.The status may be sent from the application to the fixed home office, soa dispatcher at the home office is aware of the locations of servicepersonnel in the field.

By way of non-limiting examples, the mobile device 52 may comprise aportable or laptop computer; a computer having an embedded Router 200; aterminal or terminal emulator; a data gathering device (e.g., a SCADAsystem or remote telemetry system for obtaining data from a remotelocation for forwarding to a central location for processing); acard-swipe reader device (e.g., credit/debit/bank cards) for use in amobile billing application, such as a taxi or mobile food cart; asmart-card reader; a logging device, such as those used in a packagedelivery system or fleet; a device for reading bar codes (e.g., forinventory control); and a remote application with data to send or toreceive, from a fixed application or device (e.g., remote diagnostictool). The above-noted applications are provided merely for exemplarypurpose, and other applications and mobile devices 52 may be used withthe Router 200 of the present invention.

Typically the device or Application 52 sends and receives data using avariety of protocols (e.g., Internet Protocol (IP)/transparent (via MDC54)/ack-nack, etc.). The use of a variety of protocols provides for opentransport of data throughout many networks, and in particular, networkswhich support open standards such as IP. However, many proprietarynetworks which require interface and/or protocol translation remain inuse. In the Router 200 of the present embodiment, the function ofinterfacing with networks and protocol translation may be performed bythe Network Interfaces 214A-D.

According to another aspect of the invention, other types of devices maybe connected to the Network Interface 214. Such devices may be used forfunctions other than data and voice communication. By way ofnon-limiting examples, these devices may include Global PositioningSystem (GPS) receivers and application processors.

The Router Core 204 is a function which shuttles messages between theApplication or Device 52 and the various Networks. In accordance withthe present embodiment, the router Core 204 may control which network ofa plurality of usable network messages are to travel over, and connectaccess ports (described below) to each Network and the Application orDevice 52.

The Router Core 204 may also comprise a list of all possible “names” or“addresses” to which data may be sent, or from which data may bereceived. The local “names” or “addresses” of the Router Core 204 arestored in tables within a memory (not shown) of the Router Core 204.Thus, the Router Core 204 may serve as a communications “address book”for the Router 200 of the present embodiment. The Router Core 204 alsochecks all messages passing through, and decides, based on the addressand/or name entries in the tables, if the message is relevant to theattached Application or Device 52, or to the fixed host (e.g., RNC 20).The address of the fixed host may be stored in the Router Core table aswell. In accordance with the table entries, received messages may bedetermined to be valid or invalid. The Router Core 204 may also actuatethe Switch 212 in accordance with the output of the decision process206. The Switch 212 is actuated such that incoming and outgoing messagescan be sent through the “current” network, as determined by the decisionfunction 206 (to be described below).

The Switch 212 may comprise a message multiplexor, i.e., the Switch 212performs a one-to-many function for in-bound messages (to the fixedhosts), and a “many-to-one” function for outbound messages (from thefixed host). As noted above, the appropriate network selection is madeby the Router Core 204 in accordance with the output of the decisionprocess 206. Messages travel through the Switch 212, the Router Core204, and the current Network Interface 214.

Referring to FIG. 32, the Switch 212 may be implemented using acombination of hardware (e.g., multiple electronic ports, one perNetwork Interface 214) to perform the physical connection process 212B,and software (e.g., handlers which are interrupted at each character tomove the character to either the Router Core 204 (outbound), or to thecurrent Network Interface 214 (in-bound)) to perform the switch logicprocess 212A.

As a non-limiting exemplary hardware implementation, the Switch 212 maycomprise an 80386EX microprocessor, running at 33 MHZ, 256 kilobytes ofFLASH ROM, 512 kilobytes of static RAM, six asynchronous serial ports,two TTL-to-RS232 convertors interfacing with two of the six serial portsdirectly to compatible devices external to the Switch 212, and fourinternal TTL serial interfaces to internally-mounted daughter boards,which carry Network Interfaces 214A-D. Each Network Interface 214mounted on a daughter board may include a power supply for the NetworkInterface, a serial interface to the 80386EX microprocessor, and aninterface to the outside network. The outside network may be a radio, aLAN, an antenna (for internally-mounted radios in the Network Interface214 ), or other device accepting or supplying data from/to the Router200.

The Switching function of the Switch 212 is provided by each serialNetwork Interface port at the 80386EX microprocessor, and the softwareresiding in FLASH ROM. The software logic determines which NetworkInterface to use for transmission and receipt of data. The decision isimplemented in the Switch, by selecting a physical serial port (andtherefore which Network Interface) is to be used as the current Network.The Decision software in the FLASH ROM instructs the microprocessor tosend the data to a specific serial port (which is mapped to specificphysical addresses within the address range of the 80386EXmicroprocessor). The microprocessor then constructs the next message inthe message buffers in RAM, and sends the message through the specificserial port which is designated as the “current Network” Interface port.The data then goes to the Network Interface (e.g., network interface214A) connected to that specific serial port and on to the Networkinfrastructure. Received data is input to the Network Interface (e.g.,network interface 214B which may be set to the “current Network” serialport) and the microprocessor, where the received data is processed bythe microprocessor. In accordance with an aspect of the presentinvention, messages which are received through Network Interfaces whichare not designated as the “current Network” are ignored.

The Network Interfaces 214A-D are devices which present data to, orobtain data from the radio operating at the various R.F. Networkfrequencies, bandwidths, and modulations. The Network Interfaces 214A-Dmay provide a port through which messages pass, to and from the Switch212. The messages are typically in the form of a sequence of serialdigital bits. The Network Interfaces 214A-D also may provide amodulator/demodulator function which transforms the digital data into ananalog form which may be easily sent through the R.F. Network voicepath,based on characteristics of the assigned frequency band of the R.F.Network. The characteristics of analog transmissions are typicallybandwidth (in Hertz, or cycles per second), noise present in theNetwork, and assigned frequency of the R.F. Network. Further, theNetwork Interfaces may interface with a radio, which may be includedwithin the Network Interface 214, or may be mounted externally to theRouter 200 (as shown in FIG. 29). The Network interface 214 radiointerface comprises the actual physical connections to the radio for thevoicepath data, the muting function (if present and/or required) and thefunctionality for issuing a Press-to-Talk to the radio, and forreceiving the Transmit Grant signal from the radio; both are used forhandshaking between the radio network and the Network Interface 214.This handshaking may be necessary for proper timing of the data out ontothe RF Network. The muting function is used for silencing receivedsignals which represent data, rather than voice traffic, which enables aremote user to mute the audible noise of the data traffic, which can beannoying to the remote user.

Examples of Network Interface 214A-D include the MDC 54 and the NovaTelWireless NRM-6812 Cellular Digital Packet Data (CDPD) modem. Where thenetwork interface 214 comprises the MDC 54, the radio is mountedexternal to the MDC 54, whereas in the NovaTel example, the radio andthe network interface are integrated into a single unit.

As noted above, the Network Interfaces 214 provide connections tovarious types of networks. These networks may be wired (for examplePublic Switched Telephone Network 58), or wireless (for example CellularDigital Packet Data (CDPD)). The following non-limiting list includesnetworks that may be interfaced to the Router 200 by the NetworkInterfaces 214A-D: private voice radio including conventional andtrunked radios (e.g., using MDC 54), Cellular Digital Packet Data(CDPD), Spread Spectrum (e.g., direct sequence and channel-hop), GSM,GPS receiver, satellite transponder, RDI (Ericsson) interface, AMPS, RAMMobile (Mobitex), RS232, RS485, Angel (AT&T), Asynchronous TransferMethod (ATM), Integrated Services Digital Network (ISDN), publicswitched telephone network (PSTN (POTS) telephone network), Ethernet,Ardis, Personal Communications Services (PCS), and any other networkwhich is either transparent or operates using a specific protocol.

The specific protocols to the above-listed networks are implemented inthe Network Interfaces 214A-D. These protocols may be very different,and therefore incompatible with each other. Additionally, a translationdevice may be provided in each Network Interface 214 to translatebetween IP and the particular network protocol. By providing such atranslation device, the Application or Device 52 can use IP dataregardless of the particular network the Application or Device 52 isactually using.

Referring to FIG. 31, a description of the functional components of theRouter 200 will now be described. The Router 20 may be implemented as anautonomous device with multiple connections to the networks throughwhich data is to be routed. The user Configuration Interface 208provides a means whereby an external device such as a keyboard/terminalmay be used to supply configuration information such as preferredroutes, network node addresses, etc. to the router. Such information isaccepted by the Configuration Interface 208 and is placed into anon-volatile store (e.g., memory) which may be queried by other routercomponents. In addition, capability may be provided whereby diagnosticinformation may be requested from the router and sent to the terminaldevice for evaluation by a technician.

The Router Core 204 is responsible for making all routing decisions. Fora given destination network address specified within a data packet ordatagram received from one of the network interface drivers 215A-D, themost-preferred path will be selected and the data packet or datagramforwarded through the preferred network interface driver 215A-D. Routingdecisions are generally based upon such metrics as network speed andinterface availability. Other metrics such as destination network, timeof day, type of data, etc. may also be incorporated into the routingdecision. Further, routing decisions may be made at the packet levelsuch that each individual packet of data may be transmitted and/orreceived on different networks in accordance with the user configuredparameters 208.

Exemplary Network Drivers 215A-D may include an Ethernet Driver, aToken-Ring Driver, and a Serial PPP Driver. The Ethernet Driver providesa means for sending and receiving data through an Ethernet-type network.The function of the driver is to shield the Router Core from the detailsof network media access. The Token-Ring Driver provides a means forsending and receiving data through a Token-Ring-type network. Thefunction of the driver is to shield the Router Core from the details ofnetwork media access. The Serial PPP Driver provides a means for sendingand receiving data through a PPP-based serial data link. The function ofthe driver is to shield the Router Core from the details of networkmedia access. Other drivers 215A-D may be provided to interface withother types of networks as necessary.

The Network Availability 210 (see also FIG. 30) is a function whichperiodically interrogates each installed Network Interface 214 in theRouter 200 and may determine if the Network Interface 214 is installed;if the Network Interface 214 is properly configured and functioningproperly; if the Network Interface 214 is connected to the Network,on-line, and available for sending/receiving messages; and if theNetwork Interface 214 is in good health. The above interrogation processmay be accomplished by monitoring a timer tick (provided by the switchmicroprocessor), which instructs the Network Availability 210 to queryeach Network Interface 214. When the timer tick occurs, the NetworkAvailability 210 function interrogates each Network Interface 214 asnoted above. The status of each Network Interface 214 is then passed tothe Decision process 206, which determines what the “next Network” willbe if the result of the interrogation indicates that the “currentNetwork” is experiencing transmission problems.

The Network Availability 210 of each Network Interface 214 is determinedin a manner specific to the particular interfaced Network. For example,if the Network is CDPD, the Network Availability 210 interrogates thenetwork to determine if the Network Interface 214 is currentlyregistered with the Network, and therefore active. Also, in the CDPDnetwork, the Network Availability 214 determines if the Received SignalStrength Indication (RSSI) is sufficient to transmit relativelyerror-free data. For example, in the NovaTel CDPD Network Interface aRSSI of −100 dBm will provide for good data transmission qualities.Thus, if the Network Availability 210 function queries the NovaTel CDPDNetwork Interface for the RSSI, and the response is −110 dBm, then thesignal is too weak for error-free transmission, and therefore cannot beused at this time. This information is passed to the Decision process206 to determine if the “current Network” should remain the “currentNetwork”, and if not, to determine what the “next Network” should be.

The User Configuration 208 block is used to define user configurableparameters by which the Router Core 204 selects the “current Network”and the “next Network”. The Router parameters may include the date andtime (e.g., yr-mo-da, hh:mm:ss), and the Network Interface 214 installedin each of the internal slots of the Router 200. According to thepresent embodiment there are six internal slots to accommodate NetworkInterfaces to any of private voice radio using e.g., the MDC 54 and avariety of radios, both conventional and trunked; Cellular DigitalPacket Data (CDPD), such as Sierra Wireless or NovaTel CDPD modems;spread spectrum, either direct sequence, or channel-hop, as XetronHummingbird spread spectrum modem; GSM, such as Ericsson serial GSMmodule; GPS receiver, such as Motorola VP Encore GPS receiver, orTrimble SVEE Six receiver; satellite transponder; RDI (e.g., Ericsson)interface, implemented via a software protocol module and quasi-RS232interface to radio; AMPS; RAM Mobile (e.g., Mobitex); RS232 default andfixed for example in slots 1 and 2; RS485; Angel (e.g., AT&T); ATM;ISDN; PSTN; Ethernet; Ardis; PCS; any other network which is eithertransparent or operates using a specific protocol; and none. Althoughsix slots are disclosed herein, other numbers of slots may be provided.

Other user configurable parameters include: the priority of eachinternal slot, (e.g., 1 to 6) where the slot with priority 1 is thedefault startup slot and Network; baud rate of each slot (a default ratemay be set to 9600 bits per second, but may be configured to be anystandard baud rate, divisible by 300, up to 115.2 kilo bits per second);cost per kilobyte per slot (e.g., $0.xx per kilobyte where the leastcostly slot that is available and highest priority will be default);protocol per slot (e.g., none, Point to Point (PPP), Serial LineInternet Protocol (SLIP), Hayes “AT” commands, transparent); slot mode,for example, transparent, PSTN, cellular, IP, receive only; slot name oraddress or phone number; slot to be used for diagnostics (e.g., defaultmay be set to slot 2); slot muting to be used (e.g., none, PL, DTMF,other); number of retry transmissions per Network Interface (per slot)before declaration of Network Interface failure (e.g., 0-10); if slotNetwork Interface needs to be configured before it can operate (e.g.,y,n); slot to be used for remote display (e.g., default may be set toslot 2); slot to be used for Device or Application 52 (e.g., aconnection to a mobile computer; default is slot 1); and frequency atwhich Network Availability 210 is checked (e.g., default may be set tofive seconds). Other user configurable parameters may be introduced andconfigured as necessary.

The User Configuration 208 function provides the user with thecapability to instruct the Router 200 how to select a particularNetwork. These metrics may include, but are not limited to: whichNetwork is connected to which Router port, time of day and date,priority (switching sequence) of each Network, cost per packet of eachNetwork, and preferred default Network.

On power up, the User Configuration 208 is checked to determine if it iscurrent. If the User Configuration 208 is determined to be out of date,the end user is requested to input a configuration. The user is notifiedby blinking LEDs on the front panel or by a message sent to the mobiledevice 52. If the User Configuration 208 is determined to be current, nouser input is requested.

Further, each Network is continuously evaluated for health andconnectivity status. There are a number of parameters which are examinedto determine this, including, but not limited to: Received SignalStrength Indication (RSSI), Clear to Send (CTS), Channel Clear/ChannelReady, and Transmit Grant.

The Decision process 206 continuously examines the User Configuredparameters in the user configuration block 208, to determine the nextNetwork to use, in case the current Network becomes unavailable to sendor receive data. Such an unavailability may arise because the remoteuser (and consequently the Router 200) has moved beyond coverage of theNetwork, or because a problem has occurred with the current Network orthe Network Interface 214.

After the Decision process 206 has determined the next Network to use,the decision process 206 queries the Network Availability 210. If thenext Network is available, then the Decision process 206 updates therouting tables in the Router Core 204. The Router Core 204 will thenactuate the Switch 212 to physically connect the next Network as thecurrent Network.

The Decision process 206 uses the User Configuration 208 parametersdefined above to determine the specific criteria for each slot, to beused when deciding if the current Network is to remain the currentNetwork, and if not, what the next Network shall be. Once the decisionprocess 206 has made a tentative decision to switch to another Network(i.e., the next network is to become the current network), it checks theNetwork Availability 210 to ascertain if the Network is actuallyinstalled, configured, on-line, and in good health. For example, if thecurrent Network is configured as priority #3, and the NetworkAvailability 210 of the priority #2 Network updates to, for example,“installed, configured, on-line, and in good health”, then the priority#2 Network becomes the next Network. The Decision process 206 willinstruct the Switch 212 to switch the priority #2 Network to the currentnetwork. Should the Decision process 206 decide to change Networks, itconveys an instruction to the Router Core 204 by instructing the RouterCore 204 what the next Network Interface 214 is to be.

The process of the Decision process 206 checking the User Configuration208 and the Network Availability 210 continues indefinitely, and isdescribed in detail in FIGS. 33-36. Generally, the process helps toguarantee that the mobile user always has access to a Network forsending and receiving data. This process also allows what is known nowas “seamless roaming”. This means that the mobile user can move betweenNetworks and continue to have reliable data transmission on thedifferent Networks.

FIGS. 33-36 illustrate the logic of the software in the router.Referring now to FIG. 33, there is shown an exemplary initializationroutine which builds the tables in the Router 200. Upon initializationof the system, at Step 310 the first channel priority is checked. AtStep 312, it is determined whether or not the first channel is beingexamined. If it is the first channel, at Step 314, table entries for thefirst channel are built. Information which is included in the table maybe, e.g., IP address of the destination, intervening intermediate IPaddresses, the assigned port, channel priorities, and the applicationbeing used. Typically channel one is assigned the highest priority.After the tables are built, the processing increments to the nextchannel at step 316. From Step 316, processing returns to Step 312. Ifat Step 312 it is determined that the channel being checked is not thefirst channel, processing proceeds to Step 320 to query whether allchannels have been checked. If all channels have not been checked,processing returns to Step 314 to continue building the table entriesvia steps 314 and 316 until all channels have been checked.

Once it has been determined that all channels have been checked, at Step322 it is determined whether any tables have been built. If no tableshave been built, at Step 324 a configuration error is recognized and theprocessing stops. Tables may not have been built previously, e.g., ifthere are problems with the IP address, i.e., there was no destinationaddress. If at Step 322 it is determined tables were already built,processing proceeds to Step 326 where all channels are initialized anddata transportation begins via the first channel.

From Step 326 the processing proceeds to Step 328, also shown in FIG.35, which illustrates an exemplary flow diagram of the Router 200 logicfor accounting the Network Availability 210 (FIG. 30) and UserConfiguration 208 (FIG. 30) to decide which channels to use for datatransport. Beginning at Step 328, processing proceeds to Step 330 wherethe channel is set to the current channel in a database which isdescribed in more detail below. From there, processing proceeds to Step332 to retrieve the next channel to switch to from the database. Thedatabase is stored in flash memory and contains configurationinformation for each channel including how each channel is set up in theRouter 200 and what configuration values are for each Network Interface214A-D. In addition, the database stores which channel is current andthe history of previous current channels. The tables discussed withreference to FIG. 33 at Step 314 are also stored in the database.

At step 334 a determination is made as to whether the previous channelis available. Of course if this is the first time through, no previouschannel will exist. If the previous channel is not available, at Step336 a determination is made as to whether the next channel is available.If the next channel is available, at Step 338 a determination is made asto whether or not the priority is lower and it is time to switch. Thedetermination is made by looking at the information in the UserConfiguration 208 (FIG. 30). If it is time to switch, at Step 340 aswitch to the next channel is made. From there, processing continues tostep 341, where it is determined if the channel was switched. If thechannel was switched, processing continues to step 343 where a ping issent to confirm the path is available. From step 343, the processingcontinues to Step 342, also shown in FIG. 34. If, at step 341, it isdetermined the channel was not switched, processing continues to step342.

Returning to Step 334, if it is determined that a previous channel isavailable, at Step 344 an inquiry is made as to whether or not theprevious channel has a higher priority and it is time to switch. Thedetermination is made by consulting the information in the UserConfiguration 208 (FIG. 30). If it is determined the previous channel isa higher priority and it is time to switch, at Step 346 a switch to theprevious channel is made. From Step 346, the processing proceeds to Step341 as previously described.

If at Step 344 it is determined that it is not time to switch and thepriority is not higher, processing proceeds to Step 336 where it isdetermined whether the next channel is available. If the next channel isnot available, at Step 348 the current channel is not switched and theprocessing proceeds to Step 341 as described above. If at Step 336 thenext channel is available, then at Step 338 the inquiry into priorityand time to switch is made as previously described. At Step 338, if itis not time to switch and the priority of the next channel is not lower,the Router 200 stays on the current channel at Step 348.

Refer now to FIG. 34 which illustrates a flow chart of exemplary logicfor checking the availability of each network interface. Starting atStep 342 processing proceeds to Step 344 where the status of the channelbeing used is recorded in the database. Furthermore, at Step 344, theRouter 200 front panel LED's are updated. If at Step 346 it isdetermined the availability of all channels has not been checked, atStep 348 the next channel is identified and at Step 350 the nextchannel's availability is polled. A channel is not available if it isbeing used for a mobile device 52 i.e. the channel is already one end ofthe network. If the channel is not available, the processing returns tostep 348. If the channel is determined to be available at step 350,processing proceeds to Step 328 also shown in FIG. 35.

If at Step 346 it is determined that the availability of all channelshas been checked, at Step 352 the availability of the present channel isdetermined. If the present channel is available, a connection is made atStep 354. If the present channel is not available, processing proceedsto Step 356 for error handling. The error handling procedure isdiscussed with reference to FIG. 36 below. Upon completion of the errorhandling procedure, at Step 360 the channel is set equal to one at Step362. At Step 350, the procedure continues as previously described.

Referring now to FIG. 36, which is an exemplary flow diagram of theRouter 200 error handling logic, Step 356 continues from FIG. 34. AtStep 370, the present channel is deemed to be non-available. At Step372, the next and previous channels are also confirmed to benon-available. At Step 374 an error is indicated to the device orapplication. At Step 376 an availability routine is run such as thatdescribed previously. From the availability routine at Step 36, theprocessing continues to Step 360 as discussed with reference to FIG. 34.

The Router 200 of the present invention may be used inside a mobilevehicle, or carried by a person in a portable application. Further, theRouter 200 may be provided as an external component connected to aportable device (e.g., a laptop computer) or may be implemented withinthe portable device, such that the portable device and the Router 200are provided as one integrated unit. Further, the Router 200 may be usedin conjunction with, or integrated into measuring and testing equipment,and transmission equipment. Such a remote device may be needed for veryremote monitoring applications, such as wildlife studies, etc.,necessitating the use of multiple Networks.

Referring now to FIG. 37, there is shown the software architecture 219of the Router 200 in accordance with an embodiment of the presentinvention. The architecture is strictly layered in that data flows onlyvertically between adjacent layers. The definition of each layer willnow be described.

The Application layer consists of various processes that performservices directly related to the function(s) for which the device isdefined. This includes such services as defining a device configuration,making decisions about which route to select for the transport of dataand performing various diagnostic functions.

The Presentation layer consists of a protocol-independent insulatinglayer between the applications and the lower-level networking functions.The Presentation layer implements a Berkley sockets compliantapplication programming interface (API).

The Networking layer performs all processing related to handling theInternet Protocol (IP). The main function of the networking layer inthis environment is the routing of data passed into the layer fromeither above or below back out through selected Network Interfaces todeliver that data to the intended destination. The relationship ofdestination and network interface is maintained by the ConfigurationModule and Routing Decision Module applications.

The Data-Link layer provides logical Network Interfaces through whichthe Networking Layer may send and receive data. One or more of theseNetwork Interfaces may be active at any time. At least one networkinterface must be active for the device to function properly. The mainpurpose of the Data-Link layer is to insulate the Networking layer fromthe details of the many link-level protocols used to transport data.

The Device-Specific layer deals with the details of establishing andmaintaining data communications through various types of communicationdevices such as radios, modems and data controllers. EachDevice-Specific driver handles the vagaries of configuring andinterfacing with various types of communication devices while presentinga uniform interface to the Data-Link layer.

The Physical Interface layer handles the direct interface to externalcomponents. For example: A serial port driver may handle the sending andreceiving of individual data bytes through a specific type of serialcontroller such as an Intel 8250.

A description of the functionality supported by various module blocks aspresented in FIG. 37 will now be described.

The Configuration Module 222 is an Application layer module that allowsa technician to maintain a database of device configuration information.A technician may access the Configuration Module via a diagnostic serialport. Another implementation may allow a technician to access theConfiguration module through any of the defined Network Interfaces via astandard socket.

The Routing Decision Module 220 selects the preferred network interfacethrough which outbound data is transmitted. This decision is based upona variety of metrics including: Interface availability; Time of day;Type of service required; Interface priority and others. Examples ofvarious routing metric schemes are presented later.

The TCP/IP Socket Interface 224 supports an Application ProgrammingInterface (API) which, for example, conforms to the standard Berkleysockets paradigm. Its purpose is to shield the Application Layer fromthe details of the underlying networking protocols. It allows differentnetwork implementations to be employed without the applications beingrequired to adapt.

The TCP/IP Router/Gateway 226 implements standard IP host support withthe additional capability of being able to act as a gateway betweenmultiple networks. IP datagrams received by this layer that are notdestined for a local IP host address are forwarded through the networkinterface that is currently designated as the preferred route for thegiven destination address. It is possible that the management andselection of preferred routes is implemented by the Routing DecisionModule 220 in the Application layer.

The PPP Protocol Driver 228 provides a network interface whose data-linkprotocol conforms to the Point-To-Point protocol standard. The SLIPProtocol Driver 230 provides a network interface whose data-linkprotocol conforms to the Serial-Line Internet Protocol de factostandard. Other protocol drivers 230 may be implemented which provideNetwork Interfaces which support either existing protocols or futureprotocols. The intent is to convey that the underlying link-layerprotocol is transparent to the upper and lower layers and thatadditional protocols may be easily supported.

The MDC Interface Driver 234 provides device-specific support for MobileData Controller 54, as described above. The CDPD Interface Driver 236provides device-specific support for a Cellular Digital Packet Datacontroller. Other device-specific drivers, e.g., Modem “X” InterfaceDriver 238 may be implemented to support current or future devices.

The Serial Port Driver 240 deals with the hardware aspects ofasynchronous serial data communications such as manipulating a SerialI/O controller or other such external interface. Other physical layerdrivers 242 may be implemented which support different externalinterface devices either existing or in the future.

Although the invention has been described herein with reference toparticular means, materials and embodiments, the invention is notintended to be limited to the particulars disclosed herein; rather, theinvention extends to all functionally equivalent structures, methods anduses, such as are within the scope of the appended claims.

For example, the router of the present invention may be included as aninternal component of the mobile device, proving for an integratedmobile device. Optionally, the router may be implemented entirely as asoftware process running on, for example, a portable personal computer.In such an implemention, the internal slot(s) of the personal computermay be provided with network interface(s) and a software program mayserve as the router core. Further, data may be routed to the differentnetworks at another level than at the packet level. For example, entiremessages may be routed over various networks if such a configuration isrequired.

What is claimed is:
 1. A router for use in a system comprising a firstdevice and a plurality of remote devices, the first device beingconnected to a plurality of networks so that the plurality of networkscan be monitored during a transmission, each of the remote devices beingconnected to one network or the plurality of networks so that theplurality of networks can be monitored during the transmission, at leasttwo of the networks being dissimilar, autonomous, parallel, andconnected to both the first device and a selected one of the remotedevices, the router comprising: a first interface for connecting to theplurality of parallel dissimilar networks; a second interface forconnecting to the selected remote device; a monitoring system thatmonitors the status of the plurality of parallel dissimilar networksconnected to the selected remote device, the plurality of paralleldissimilar networks being available for data transmission; and aselector that selects at least one available network from the pluralityof parallel dissimilar networks for transporting data between the firstdevice and the selected remote device when a single transmission isinitiated, wherein the transmission can occur over the plurality ofparallel dissimilar networks when the single transmission is initiated;and wherein the transmission occurs while the router switches from afirst one of the plurality of parallel dissimilar networks to a secondone of the plurality of parallel dissimilar networks.
 2. The router ofclaim 1, in which the router switches networks immediately aftertransporting a first data packet and before transporting a subsequentconsecutive data packet.
 3. The router of claim 1, in which the statuscomprises at least one of installation status, network health,configuration status, and network availability.
 4. The router of claim1, in which the monitoring system determines whether a next network isavailable for data transport.
 5. The router of claim 4, in which theselector selects a next available network from the plurality of networksin accordance with network selection criteria when the monitoring systemdetermines that the at least one available network becomes unavailablefor data transport.
 6. The router of claim 5, in which the routerswitches to the next available network, immediately after transporting afirst data packet and before transporting a subsequent consecutive datapacket, when the monitoring system determines that the at least oneavailable network is unavailable for data transport.
 7. The router ofclaim 1, in which the plurality of parallel dissimilar networks comprisewireless networks.
 8. The router of claim 1, in which the plurality ofparallel dissimilar networks comprise at least one wireless network andat least one wireline network.
 9. The router of claim 1, furthercomprising a system for interfacing protocolized data into the pluralityof parallel dissimilar networks using different protocols.
 10. Therouter of claim 1, in which the plurality of parallel dissimilarnetworks comprise switched networks.
 11. The router of claim 1, in whichthe plurality of parallel dissimilar networks comprise dedicatednetworks.
 12. The router of claim 1, in which the plurality of paralleldissimilar networks comprise switched networks and dedicated networks.13. The router of claim 1, in which the plurality of parallel dissimilarnetworks comprise at least one of digital networks and analog networks.14. The router of claim 1, in which at least one of the plurality ofnetworks comprises a packet based wireless network.
 15. The router ofclaim 1, in which the data comprises digital data.
 16. The router ofclaim 15, in which the digital data further comprises digital voice.